iTunes Windows keeps asking me to authorize.

So I bought DragonForce's Ultra Beatdown album on my phone. I try to play it on my computer, Heroes Of Our Time is the only song it can play. Any other one, it'll ask me to authorize. I do so, then I play it, then it askes me to authorize again. But, here's what I noticed, when it asks me to authorize, it puts my old email to the account as a placeholder, but I changed the email to my account a while back on my phone, so I'd also like to know how do I change my email to the one I'm currently using on iTunes Windows, to authorize only once? Hopefully this makes sense. I looked at my account info on my pc, and it does show the current email I'm using, so I wonder why it still tries to use my old email, when it doesn't work anymore. I tried signing back out and back in, it managed to fix putting my old email as a placeholder, but it still wants me to authorize my computer, even after I have so many times.