Have you ever fired up an iOS device and been prompted to enter the password for some Apple ID that’s not yours? This is especially likely to happen on a newly purchased device, when bulk music and apps are being loaded for the first time.

Typically, this happens when you have apps or music on your computer purchased by someone else’s Apple ID (obviously), but which your computer is no authorized to play.

If you know the offending track or app, you can just delete it, or rebuy it under your usual Apple ID. But there are situations where you are prompted to enter a password without context. And that’s the tricky part, especially if your library is big.

If you know your library pretty well, one path you can take is to select each app or track in iTunes and select File > Get Info, or type ⌘-I. When the info window appears, click on the File tab and you’ll see the Apple ID that made this purchase.

If you’ve got a ton of music tracks to sort through, get yourself a copy of Track Down Purchases, from Doug’s AppleScripts for iTunes. For free, it will sort through your music library and report a list of Apple IDs along with the number of tracks for each. And for $1.99 (in application purchase), it will build playlists for each Apple ID so you can easily delete the ones to which you no longer have access.

Note that in El Capitan, iTunes scripts go into your user folder > Library > Scripts > Applications > iTunes.

Know of another approach to solving this? Please leave a comment.