Q: Trying to change my billing information but I keep getting a request for security code which I imputed but still getting the same question. What am I doing wrong?

Hello there, Pekoj.

The following Knowledge Base article offers up some practical review of how to change your payment information:

iTunes Store: Changing your payment information

http://support.apple.com/kb/ht1918

One thing you can try is signing out and back into your Apple ID. If reviewing these steps does not resolve your issue, the Get Help section provides the following:

If you need help changing your payment information, contact iTunes Store support.

Thanks for reaching out to Apple Support Communities.

Cheers,

Pedro.