Under “Subscription & Billing” click “Edit” on the row marked “Payment Method” (Note: if you have a free or comped account, you will not see this option)
Find the payment method you wish to update and click “Edit”
If a card number has changed, you will need to create a new payment method instead of editing an old one. To do that, click “Add new payment method” (located at the bottom of your list of payment methods)
You can also delete a payment method by clicking “Edit” and then “Delete”