You can update your billing/payment profile by following the instructions below:

1. Login to your account and click the "Account" button at the top of the screen.

2. Click "Billing Menu and then "Payment Profiles and Recurring Billing" in the control panel

3. Update the necessary information and click the "Update Profile" button near the bottom of the screen.

As long as it does not give you any errors, the payment profile has been updated.