While rare, you may notice an issue with OnSong after updating iOS on your device.  If you are experiencing an issue with OnSong that is abnormal, you can reinstall the app after backing up your library to correct most issues.

First, make sure that you have backed up your OnSong library to a remote location like Dropbox.  You can learn how to backup and restore your OnSong library here: http://onsongapp.com/videos/backup

Once you've backed up OnSong, you can delete the app from your home screen.  To do this, tap and hold on the OnSong icon on your home screen until the icons jiggle.  Tap on the "x" icon in the upper left corner of the OnSong app icon to delete the app.  You will be prompted that your data and documents will be deleted.  If you agree, the app will be removed your your device and you can tap on the home button or swipe up on the screen to exit the home screen editing mode.

Next, go into the App Store app on your device and view your account.  In there you should see a Purchases section.  Open this to be displayed a list of your purchased apps including OnSong.  You can then reinstall OnSong on your device.

Once completed, you can then restore your backup per the backup instructions.