On rare occasion, you may need to reinstall OnSong. Some users have reported strange issues after an update from the App Store. You can reinstall OnSong by backing up your library, deleting the app, and then reinstalling from the App Store.
The first step is to backup your library and remove the backup from your device. The best practice for this is to backup your library to Dropbox, Google Drive, or use iTunes File Transfer to transfer the backup file from your device to your computer using a sync/charge cable. While OnSong should retain your library after deleting the app, it is best to have a backup anyway. Keep in mind that this single backup file contains all your songs, sets, styles, settings, etc. It only contains the currently selected library, so if you have multiple libraries, you'll want to backup each individually.
Now that your library is safe, go to the home screen on your device. Tap and hold to bring up a menu of options and choose Delete App. On older iOS versions, this may cause the apps on the screen to jiggle with a small "x" icon. Tap on the "x" icon and agree to the prompt. You can then tap on the home button, or swipe up from the bottom of the screen to leave the icon organization mode.
To reinstall OnSong, open the App Store app from your home screen and open the account profile screen by tapping on the user icon. You can then locate OnSong in your list of purchased apps and download again. You can also search for OnSong in the App Store and download as well. If you are prompted to purchase OnSong, it is likely because you are not actively logged into the App Store. As long as you are using the same Apple ID you used to purchase OnSong previously, you will not be charged.
If your library is not immediately available, you can import the backup file you made in the first step. To do this, open the Songs Menu by tapping on the "Songs" button in the Menubar and then choose the Songs tab at the bottom to view your list of songs. Tap on the "+" button to open the Add Songs Menu. You can then browse for your backup file and import it to restore your library. You can learn more about the backup/restore process in our video tutorial.