1. On the iPhone's lock screen, touch and hold anywhere on the display until you see the Customize button. You'll need to ...

Your screen will then change to show you how this mode will look. Note that this can be changed back to light at any time by simply choosing the Light option, or toggle on the Automatic switch to ...

Press the Mode button for about two seconds ... swipe down from the main screen and select the icon that looks like a person speaking. To set up automatic shutoff, swipe down on the display ...