From the Apple menu, choose System Preferences. Click Desktop & Screen Saver. Click Screen Saver, and then use the slider to choose 15 minutes (or less).

How do I change inactivity timeout on Mac?

Choose System Preferences from the Apple menu, then click Energy Saver. Use the slider to choose the time of inactivity. If you set your display to turn off before the screen saver starts, the screen saver won't start after a period of inactivity.

How do I stop my Mac screen from turning off?

To turn off sleep mode on a Mac, go to System Preferences > Energy Saver. Then tick the box next to Prevent computer from sleeping automatically when the display is off and drag the Turn display off after slider to Never.