i put new os to my compters but it is not authorzing to itunes, i put new os to my computers but it is not authorsing to itunes

Hello there, kgnplaza.

Sounds like over time you may have authorized enough computers to reach your limit of 5. The following Knowledge Base article provides the steps for deauthorization so you can start anew:

iTunes Store: About authorization and deauthorization

http://support.apple.com/kb/ht1420

Particularly:

To deauthorize all computers associated with your Apple ID

If you need to authorize your new computer and are unable due to already having five authorized computers, you can deauthorize all computers by doing the following:

1. Click iTunes Store on the left side of iTunes.
2. If you're not signed in to the store, click the Account button, then enter your account name and password.
3. Click the Account button again (your Apple ID appears on the button), enter your password, and then click View Account.
4. In the Account Information window, click Deauthorize All.

Note: You may only use this feature once per year. The Deauthorize All button will not appear if you have fewer than two authorized computers. If you need assistance on using this feature, please contact iTunes Store support via email (http://www.apple.com/support/itunes/store/).

Once you've deauthorized all, you will want to go back and authorize the computer(s) you are using now.

Thanks for reaching out to Apple Support Communities.

Cheers,

Pedro.