How to Change Your Mac Lock Screen

By default, it's a blurry version of your wallpaper. Luckily, there is an easy solution to unblur or change it, and that’s what we will go through in this article.

But first, there are a couple of things you need to consider before attempting to change your login background on Mac:

• The photo must be in .png or .heic file format, depending on your macOS version
• The photo should fit the resolution of your screen. Otherwise, you’ll see tons of pixels
   

Before we start
 

Personalizing your Mac can make it much more enjoyable to use. If you often feel like getting help with your Mac-related questions, MacKeeper support team are available 24/7.
 

They can help you deal with any customization tasks and almost any other tech issues you may encounter. To have a chat with our representative:

1. Download and install MacKeeper
2. Go to any tab and drop a line into the chat box
3. Our tech expert will be in touch with you in less than a minute

Below, we will share a few tricks to make sure your photo won’t get blurry. 
 

Here’s what we will discuss:

1. How to resize your image to fit Mac login screen
2. How to add your wallpaper on a Mac
3. How to change the lock screen on macOS Sierra
4. How to change login background on macOS Mojave
5. How to change screen photo on macOS Catalina
6. How to change the Big Sur login screen
7. How to change user icons on a Mac

How to resize your picture to fit Mac login screen

1. Click the Apple logo in the top left corner of your screen and select About this Mac

2. Open the Display tab and write down your Mac’s screen resolution

3. Open the picture you want to resize using the Preview app

4. Click Tools from the top panel and select Adjust Size

5. Edit the resolution of your photo according to your Mac’s screen size determined in step 2, then click OK

6. Click File from the top panel and select Save

If you want to use a photo from your iPhone, our article on how to import photos from iPhone to a Mac is also worth checking out.

How to add your lock screen wallpaper

1. Ctrl + Click on your desired login screen photo, select Open With, and choose Preview app

2. In the top toolbar, click the File tab and choose Save As

3. Choose PNG as the necessary file format and name it com.apple.desktop.admin.png

4. Save it somewhere on your Mac

5. Use the Command (⌘) + Shift + G keyboard combination to activate the Go To Folder menu

6. Copy and Paste /Library/Caches in the address bar, then click Go

7. Copy the new picture you saved as “com.apple.desktop.admin.png” and paste it to the /Library/Caches folder

You can use the Command (⌘) + C key combination to copy and the Command (⌘) + V combination to paste or just drag and drop the picture. 

8. That’s it! Log out from your Mac and enjoy your new login background picture

You’ll also see the image you chose whenever you turn on or reboot your Mac. In case you ever experience troubles with that, it is best to know what to do if your Mac won't shut down.

How to change the lock screen on macOS Sierra

If you have macOS Sierra, changing your lock screen photo can be much more comfortable. All you need to do is:

1. Open System Preferences
2. Choose Desktop & Screen Saver
3. Take a look at the left window pane to choose the photo you want to set as your new background

How to change login background on macOS Mojave

For macOS Mojave, you can change the login background screen by doing the following:

1. Ctrl + Click your desired login screen photo, select Open With, and choose Preview app
2. In the top toolbar, click the File tab and choose Save As
3. Choose HEIC as the necessary file format and name it Mojave.heic
4. Save it somewhere on your Mac
5. Open Finder and go to /Library/Desktop Pictures/
6. Paste your desired login background (you can also drag and drop)
7. Your Mac will ask for your admin password to confirm the operation, so you need to insert your user password
8. Congratulations! Now you can enjoy your customized lock and login screen

How do I change my lock screen on macOS Catalina?

Changing the lock screen on macOS Catalina can quickly be done in just a few steps:

1. Convert your image to JPG
2. Rename your image as Catalina and save it in the Downloads folder
3. Reboot your Mac and hold Command (⌘) + R to start the recovery mode
4. From the top menu click Utilities and open the Terminal app
5. Type cp /Volumes/MacHD\ -\ Data/Users/[your user name]/Downloads/[Catalina].jpg /Volumes/MacHD/System/Library/Desktop\ Pictures/Catalina.heic
6. Restart your Mac
7. Invalidate the cached image by changing any option in Preferences > Users & Groups > Login Options
8. Now you are all set up, enjoy your new lock screen.

How to add a message to the login screen

You might be wondering why would you ever need something like that? Well, this is an excellent way to add a pinch of personalization to your Mac. If your Mac ever gets lost (hopefully, this will never happen to you), a locked screen message is a good way to add some contact information.

You can add a message to the login screen by following these easy steps:

1. Go to System Preferences

2. Open Security & Privacy

3. In the General tab, check the box next to Show a message when screen is locked

4. Next, click on Set lock message…

5. Write your message. You can add your phone number or email address to the notice. You may want to even offer a cash reward for returning your Mac

6. Voila! Now your message will appear whenever the screen is locked

How to change the Big Sur login screen

1. Open Finder—click on Go in the menu bar—then choose Go to Folder

2. Type or paste the following /Library/Caches/Desktop Pictures—press the Go button

3. In the Desktop Pictures folder, you’ll see one or a few folders. They are named after the names of user’s UUIDs. Open this folder and you should see a “lockscreen.png” file. 

Note: If there’s no Desktop Pictures folder on your Mac—you’ll need to manually create such in the Caches folder. Follow these steps:

3.1 Go to System Preferences—Users & Groups—click the Lock icon in the left bottom corner—type in your admin password—right-click on your user’s name—choose Advanced Options—next copy the UUID of your User ID.

3.2 Quit System Preferences—go back to /Library/Caches/Desktop Pictures folder—create a new folder—name it with your UUID.

3.3. Next, right-click anywhere in this folder—choose Get Info from the drop-down menu.

3.4 Double-check if your Mac has Write privileges. Allow Read & Write to user, admin, and, everyone.

4. Rename lockscreen.png image (if this image is in the folder) to old-lockscreen.png

5. Rename the image you want to have as your login screen to lockscreen.png—drag-and-drop it to the open folder

6. Restart your Mac

How to change user icons on a Mac

You can also change the default stock icons that apple chose for you by doing the following:

1. Open System Preferences

2. Click the User & Groups icon

3. Hover over your user icon and click Edit

4. Choose your new image or just take a new photo using you Mac’s cam

5. Click Done to save the changes

FAQ

How do I customize my Mac screen?

To customize your Mac screen, change your desktop picture:

1. Go to the Apple menu and select System Preferences
2. Click Desktop & Screen Saver
3. From the left sidebar, select an image folder and click a preferred image

You can also customize Mac desktop picture using the Finder:

1. Open the Finder and locate a preferred image
2. Right-click the image and select the Set Desktop Picture option from the drop-down menu
3. If the Set Desktop Picture option is not available, select Services and find the option there

How do I change the lock screen picture on a MacBook Air?

To change the lock screen picture on a MacBook Air, simply change your desktop background. Since both images are connected, they will be instantly replaced with the picture of your choice. 

Here’s how to do it:

1. Open the Photos app and locate a preferred image
2. Right-click the image and select the Set Desktop Picture option from the drop-down menu

Here’s how to customize your Mac lock screen without changing the desktop background:

1. Open a preferred image in Preview
2. Double-click the image name at the top of the screen and rename it to “lockscreen.png”
3. Navigate to Finder > Go > Go to Folder
4. Enter the path /Library/Caches/Desktop Pictures and click Go
5. Out of several folders, select the one that contains “lockscreen.png” file
6. Drag and drop the preferred screen image into the folder
7. In a window that opens, click Replace

How to change the login screen background on macOS Catalina?

To change the login screen background on macOS Catalina, you have to use the Terminal app and restart your Mac. If you can spare a few minutes, here’s how to change lock screen on Mac:

1. Find a JPG image
2. Rename the image to Catalina.jpg and drag it to the Downloads folder
3. Reboot your Mac while holding Command (⌘) + R
4. Select Utilities from the top menu and launch the Terminal
5. Enter: cp /Volumes/MacHD\ -\ Data/Users/your user name/Downloads/Catalina.jpg /Volumes/MacHD/System/Library/Desktop\ Pictures/Catalina.heic
6. Restart the Mac
7. Go to Preferences > Users & Groups > Login Options and change any option

How do I make a custom screensaver on my Mac?

To make a custom screensaver on your Mac, use this method:

1. Go to the Apple menu and select System Preferences
2. Click Desktop & Screen Saver
3. In the Screen Saver tab, select a screensaver type
4. In the Source menu, select the Choose Folder option
5. Navigate to a preferred folder with images and click Choose

To set a timer for your Mac screensaver, go to the Start after menu at the bottom and select a preferred value. You will the screensaver after your Mac remains inactive for the selected time period.

Why does my Mac keep changing my desktop wallpaper after shutting down?

Your Mac keeps changing your desktop wallpaper because you’ve selected the Dynamic Desktop option in the settings. To fix the issue, go to System Preferences > Desktop & Screen Saver > Desktop and untick the Change picture box.

Another likely reason the desktop background keeps changing on Mac after a restart is an external display bug. There’s no way to address the issue other than to disconnect the display before shutting your Mac down.

The constantly changing desktop background could also be a software incompatibility already addressed by Apple engineers. Therefore, if the two previous fixes don’t help, update macOS.

Why can’t I change my lock screen wallpaper?

If you’ve done everything exactly as described in the guide, you should face no problem. However, make sure you did the following:

• You converted the file format of the photo to .png or .heic depending on your macOS edition
• You resized your image according to the dimensions of your Mac’s screen

How do I default my lock screen?

1. Open System Preferences
2. Click Desktop & Screen Saver
3. Make sure you are in the Desktop tab
4. At the bottom of the panel, you may find a Change picture option, and all you need to do is to uncheck the box next to it
5. Congratulations! You’ve successfully managed to default your lock screen

That’s it! As promised, we have provided you with all the information you need to change your Mac’s login background.