If you back up multiple iOS devices on the same computer you may run into the problem of one device recognizing the Apple ID of another when attempting to update your Apps in the App Store. Before updating it will ask you to sign into to one of the other devices Apple IDs even though your phone is logged into yours. If you run into this problem simply delete the app and reinstall it. This should do the trick and allow you to update the app the next time an update comes out for it. I hope this is useful to someone.