Hi! Updating the address for your account is definitely an important step. When completing that task you will first want to login and click the Account Administration icon in the upper right corner then go to Settings and billing.
On that page you will notice the Sender info tab located near the middle of the page and you can complete your address update there.
This will also update the address located at the footer of your campaigns. That said, if our design team created a custom template for you then it is possible your address is hard coded and will not be updated. If while testing your next campaign you notice that your address is not updated, contact our Support team to have the additional updates completed.
Please let us know if there is anything else I can do for you.