Prior to watchOS 27, the easiest way to force quit Apple Watch apps was by swiping across them in the App Switcher screen, but that's no longer possible because the Digital Crown double-click gesture that got you there is now reserved for Apple's upcoming Live Rewind AI feature. Fortunately, there's still a way to force quit apps in watchOS 27.
From the app you want to quit, press and hold the Side button until the sliders appear. Then simply press and hold the Digital Crown until the watch face appears. You've now quit the app. Quitting an app doesn't save battery power, but it's useful if the app is misbehaving.
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Top Rated Comments
The Watch has four input methods, five if you count the crown turn and press as two. Three of these are hard buttons that are very prominent and should be reserved for key OS functions.
The Digital Crown should act on the app on screen, whether that's the watch face or another app. Some faces have usable functions. Maybe Live Rewind is a Watch face with that turned on. Swipe to that watch face if you want Live Rewind.
The side button should be the app button. One press brings up the simplified honeycomb grid. Scroll up with the Digital Crown or your finger within the app grid and you get the full app honeycomb, scroll down and you see Control Centre. Two presses brings up Apple Pay. Press and Hold brings up recent apps carousel like on iOS. Swipe side to side to get back to your intended app or swipe them away to force quit them.
Consistency be gone!
I hope they make the app switching an option again, I literally use it every day to access apps I recently used quicker.