Q: Account Settings is not taking payment info; cannot download apps or music

Hey emilyazznara,

Thanks for using Apple Support Communities.

You can change the payment information from iOS or in iTunes if one of them does not work. 

iTunes Store: Changing your payment information

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

If you need help changing your payment information, contact iTunes Store support. Or you may find the answer to your question below:

• If you change your payment method, make sure your account information matches the credit card information on file with your financial institution.
• If you use an AOL screen name to sign in to the iTunes Store, editing your information on the Account Information page won't update your AOL account. If you need to update your AOL account information, contact AOL.
• If your previous payment wasn't accepted, you may need to change your payment information.

Have a nice day,

Mario