Q: Is there a way to find out what 5 computers I have authorized to share music from iTunes? I believe I only authorized 4, but I always receive the error message that I already have 5 computers authorized.
A: Unfortunately, iTunes does not offer the ability to get a listing of which computers have been previously authorized. Once you reach the limit of five computers, however, Apple does permit you to reset all of your authorizations once per year, which will essentially de-authorize all of your existing computers and reset your authorization count to zero.
To do this, simply log into your iTunes Store account page, by selecting the iTunes Store, and then clicking on your iTunes Store username where it appears in the top-right corner of the Store window.
Note that the “Deauthorize All” button will only appear once you have reached five authorized computers.
Once you have done this. You can then go through and RE-authorize some or all of your previously-authorized computers by selecting Store, Authorize Computer on each one, or trying to play any purchased audio or video track.
Also keep in mind that if you make a serious hardware change to a computer that’s already been authorized (changing the main system board for instance), or you reinstall your computer’s operating system, you will actually lose one authorization, since iTunes will see the new hardware or software configuration as a new computer. It is always a good idea to DEauthorize your iTunes Store account (by selecting Store, Deauthorize Computer) before sending your computer in for service, or reinstalling your operating system yourself.