Change Screen Saver preferences on Mac
On your Mac, use the Screen Saver pane of Desktop & Screen Saver System Preferences to make images appear on the screen when you aren’t using your Mac. You may want to do this to hide your desktop while you’re away.
To change these preferences, choose Apple menu 
> System Preferences, click Desktop & Screen Saver, then click Screen Saver.
Open the Screen Saver pane for me
List of screen savers | Select a screen saver on the left, then do one of the following on the right, depending on your choice:
|
Start after | Click the “Start after” pop-up menu, then choose how long your Mac can be inactive before the screen saver starts. If you don’t want a screen saver to start, choose Never. |
Show with clock | Display the time with the screen saver. |
Use random screen saver | Let macOS choose which screen saver to use. |
Hot Corners | Start or stop the screen saver when you move the pointer to a screen corner. Click the pop-up menu for a corner, then choose Start Screen Saver or Disable Screen Saver. To use a modifier with the hot corner, press and hold the Command, Shift, Option, or Control key, or a combination of these keys, while viewing the pop-up menus. |
Tip: Want to see how a screen saver looks full screen? Select a screen saver from the list, move the pointer over it on the right, then click Preview. To stop the screen saver and return to the preference pane, just move the pointer.