Q: Itunes telling me to authorize computer when I already have

Hello,

Here is my problem:

I tried to play a video on itunes. Itunes then told me to authorize my computer. I did so. I tried to play the video, and it again tells me to authorize my computer by signing in. I sign in AGAIN. Then a notice pops up saying that "you have already authorized this computer." This essentially creates a loop of itunes telling you to authorize the computer and then saying "you have already authorized this computer" while never allowing me to play the movie.

Here's what I tried: sign in and out, exit itunes and reopen it, restart my entire computer, update itunes.

Here's what I think is the problem: I changed my AppleID email address, and the video was bought with another email. Its the same account, but I updated the email. ( maybe updating to Windows 10 did this?)

Please help me! I can't find my ipod so I don't have a serial number to call Apple Support.