Q: I have over 7500 songs on my iPod that I keep on an external drive. I’ve had no problems switching between my laptop and my desktop. recently, I bought a new laptop and installed iTunes and hooked up my external drive. I went to the iTunes store an purchased some new music. I was asked to authorize my computer, which I did. Then I went to sync my iPod and a dialog box came up to say that there were 50 songs that could not be transferred to my iPod because they were not authorized. How do you get individual songs authorized?

– Laurie

A: There is no specific way to authorize individual tracks, as the authorization key is tied to the iTunes Store account and not the tracks themselves. Basically, as long as your authorization key has been downloaded to the computer (ie, your computer is “authorized”) all tracks purchased with that account should also be authorized to play.

The most likely case of this message is that these 50 additional tracks may have been purchased or downloaded using a different iTunes Store account from your main one. This frequently happens when multiple users share the same computer, or in some cases when a user starts out with a different iTunes Store account and later changes to a new one.

You can check which account a given iTunes Store track was purchased with by selecting the track and choosing File, Get Info. The track’s “Summary” tab will show the iTunes Store account information for that particular track.

You can either use the Store, Authorize Computer menu again or simply try to play one of these tracks. In either case, you should be prompted to enter the credentials for this second account, which will authorize the computer to play these additional tracks as well. A given iTunes library or iPod can be authorized for up to five different iTunes Store accounts simultaneously.