You can update your credit card details on the "My Account" page:
1) You can access your My Account page here or when you're logged in, click on your name or photo on the top right and choose "My Account".
2) On the My Account page, click the "Subscriptions" link.
3) On the Subscriptions page, click the "Update" link.
4) Enter your new credit card number, expiry date and security code.