To start off, I have my iPhone 5 and I purchased songs and made my itunes and apple ID account before I got my macbook laptop. After getting my laptop I synced my phone with it and it worked perfectly: the only problem is that the album art on my phone has disappeared, but that's a very minor problem. Then using the same laptop, I synched my iPod touch with it (Which uses a different apple ID). And I've authorized my laptop with both of those devices. NOW the problem is that when I try to sync my phone to my itunes on my laptop, a message appears saying that I haven't authorized this computer yet, and if I don't it'll delete all of my apps. So I authorize it with my Apple ID that I've been using on my iPhone. Then it says it's successful and I have space to authorize more computers. But as soon as that window disappears it tells me that I haven't authorized my account even though I just have!
Also, my itunes and app store on my iPhone are logged into my correct account, but when I try to update my apps it'll try making me sign in with the account that's being used by my iPod. I haven't purchased any of the apps on my phone with the older iPod account, and I can't delete the account because my brother uses it. So I can't update my apps either and I've signed in and signed out on the correct account many times and it hasn't improved anything.
I've also tried to deauthorize the computer and then authorize it again, but when I go to re-authorize it, it says that it's already authorized even though I still get those error messages telling me to authorize it! I'd really prefer not to have to restore everything, because it would just be a mess if it didn't help at all. I hope someone can help!