A. Force close the app by swiping up from the bottom of the screen (or double-clicking the home button) and swiping the app off the screen. Then, reopen the app to see if it functions better.

B. If the app continues to crash, try uninstalling and reinstalling it. Press and hold the app icon until it jiggles, tap the 'X' to delete it, then reinstall it from the App Store.