Within Teamwork Projects, when you subscribe to a Projects plan, the default email address for the invoice and subscription emails will be your site owner address.
To change this to any other email address - for example, if your accounts team have a general address where they like to manage receipts - click your profile image near the top right corner of your site, and choose 'Subscription':
On the subscription screen, click the "View Invoices" button to the right of screen to view your invoices.
Scroll to the bottom of the list of payments and here you'll find the link to update the address.
Note: Only site administrators in the owner company can access this area.
For more information see: Adding more users to your subscription on per-user plans