After logging in to your account, click on Contacts in the navigation menu to the then choose view all contacts. You can then use the Filter These Contacts and enter information for the customer(s) for whom you wish to change communication preferences by clicking the View Details.
Check or uncheck the boxes next to the communication preferences you wish to change. Please note that unchecking the box next to Active Customer will remove that customer from all campaigns and any future marketing. Click the Save Changes button to complete.