To update your firm's contact information that appears on your invoices you must be an admin user of your account.
First, click on your login name at the top right of your account, then navigate to the settings tab. You will see Firm Settings from the list on the left:
You then have the option to update your:
Firm Contact Information - Your firm's name, address and phone number will appear on all invoices:
Firm Preferences - Your firm's logo will appear on all invoices and in the top left corner of the app: