My son registered a gift card he received for $15 on my itunes account. He wants to use this money to make in-app purchases for one of his games. He was purchasing coins or something, but the process went to my account, but didn't take money from the balance of the card. I am guessing I need to change a setting, but it didn't give an option to do so. How do I go about using the gift card? The balance shows on my computer when the account is open, so I know he did it correctly, we just don't know how to spend it!