You change your payment method and billing address yourself under Payment Details.
How to change your payment method
Step 1: Go to Settings > Membership.
Step 2: Click Payment Details at the top right.
Step 3: In the payment portal, you can:
add a new payment method or replace the old one
change your name and billing address
Step 4: Save your changes. The new payment method applies from the next charge.
Which payment methods are there?
You'll find an overview in Which payment methods can I use?
My payment failed. What do I do?
It's best to update your payment method right away. Learn more in My payment failed. What happens now?