Attend any event, and someone will ask the audience to silence their cell phones. But what about your Apple Watch? To ensure that the Watch doesn’t light up as you move around and adjust your arms, swipe up on the face to display Control Center, and then tap the theater masks icon to enable Theater mode (you may have to scroll down to see it). That prevents the screen from lighting up unless you tap it, press a button, or on the Apple Watch Series 2 or 3, turn the Digital Crown. To leave Theater mode after the performance, tap the masks icon in Control Center again.