There are a couple of ways to update or add a new credit card to a person.
How to update if you have access to the card.
Either you are talking to them on the phone or they are with you in person.
Go to their Member Detail page
Use the contextual menu on the Available Payments Type credit card row to edit an existing Credit Card.
OR
Go to their Member Detail page
Click on the 'Add New Credit Card' button in the right rail
How to get the member to update remotely.
Use this method which will email them a secure link where they can update it themselves through any mobile device or web browser. When they update, you will get an email notification. After they update, make sure any existing plans they have are referencing the new Credit Card.
Go to their Member Detail page
Click on the 'Request New Credit Card' button in the right rail.
OR
Tell them to log into the Member Portal or their app to update.
The update Credit Card page is located from the sub-menu in top right corner.
Note:
This same process applies for adding a new credit card to a lead.
Go to the Lead Detail page
Click 'Edit Info' button in the right rail.
From this page you have access to all the methods outlined above