Even iOS apps occasionally misbehave — they can crash, or freeze, or otherwise stop working. If you’re new to iOS, or just haven’t had this happen before, you may not know how to actually quit an app (as opposed to just swiping it off your screen). Here’s how to quit an app using iOS 14:
Open the App Switcher by either swiping up from the bottom of the screen and then pausing in the middle, or (if you have a Home button) double pressing the Home button.
You’ll see an overlapping view of all your open apps. Swipe to the right or left until you find the app you want to quit.
Swipe up on the app.
Unfortunately, there isn’t any way to close all of your apps at once, should you wish to do so — you’ll have to simply swipe them off one at a time.
If for any reason swiping the app off doesn’t solve the problem, then shut down your phone by pressing and holding the side button and either volume button until you see sliders appear. Drag the one that says “slide to power off” to the right. (If you have an iPhone with a Home button, instead, press and hold the side or the Sleep / Wake button.)