Change Desktop preferences on Mac
On your Mac, use the Desktop pane of Desktop & Screen Saver System Preferences to change the picture or color shown on your desktop (the background area of the screen). Learn how to customize the desktop picture.
To change these preferences, choose Apple menu 
Option | Description |
|---|---|
List of pictures, colors, and folders | Select an item on the left, then click a picture or color on the right. Dynamic desktop pictures can automatically change throughout the course of the day based on your current location. If Location Services is turned off in Privacy preferences, the picture changes based on the time zone specified in Date & Time preferences. Some dynamic desktop pictures may also provide still images so the desktop picture doesn’t distract from the light or dark appearance. For example, if you chose the dark appearance during macOS setup, the desktop picture is set to a dark still image. To use or stop using a still image (if available), click the pop-up menu, then choose an option. If you don’t see anything when you select the Pictures folder, you either don’t have pictures in that folder or they don’t have the right file format—JPEG, PICT, TIFF, PNG, or HEIC. To change a picture’s format, open it in the Preview app, then save it in the new format. If pictures look fuzzy, try using larger ones, such as 1024 x 768 pixels. |
Add | To use an image from another folder, click the Add button To remove a folder you added, select it, then click the Remove button |
Fill Screen pop-up menu | When you select a picture from Photos or the Pictures folder, choose how you want to arrange it on the screen—for example, fill the screen or center the picture. Some choices may distort the picture. |
Change picture | Cycle through all the pictures available in the item or folder you selected in the list on the left. Use the pop-up menu to choose how often to change the picture; for example, every hour. This option may affect the performance of some apps, such as games, that use many graphics. |
Random order | When you choose to change pictures, you can also choose to display the pictures in a random order. |
and Remove 