Should you find that the app does not work as it should. Then you can shut down the app completely, which means you force the app to stop.
The way you do it is a little different depending on what iPhone you have.
- On iPhone X or later, slide your finger up from the bottom of the home screen and up to the center, and release the screen.
- On iPhone 8 or older, double-click the Home button.
- Now find the app in the list that appears.
- Slide up once you find the app in the list.
- Now the app should be shut down.