How to Turn on Ambient Display on Android Device
Ambient display allows you to view the time and notifications on your lock screen without having to press the power or home buttons.
Step 1. Swipe down from the top of the screen to reveal the Notification Shade. Depending on which Android phone you have, you may have to swipe twice.
Step 2. Tap on the settings button. It’s the gear icon in the top right.
Step 3. Tap Display.
Step 4. Tap the On/Off switch beside Ambient display.