purchased songs with old AOL account, itunes won't play them, nor copy them

Years ago, I used my old AOL account name as my Apple/itunes login, and purchased several songs. Since then, I've changed my Apple ID, and songs I've purchased using that login play fine on my Mac, and transfer to my ipod/iphone. However, songs I purchased with the old AOL login will not sync to ipod/iphone, and when I try to play them in itunes, it comes up with "Computer is not authorized to play. Would you like to authorize", and it has my AOL name, and it asked me to enter the password (which I remember), so I enter it, but after i enter it, it says "You need to change your account to use an Apple ID." But I already have an Apple ID. Long question short: How do I make it so my old AOL purchased songs will play on my iTunes and ipod?