To change the email address where you receive billing notifications, you need to be a workspace admin also known as a Doc Maker (Admin):
Go to your Workspace Settings by clicking on the workspace name on the left panel and then Admin settings
Select the Billing tab
Edit the Billing email address from there

To add a new Workspace Admin, please see: Promoting and Demoting Doc Makers
For any other billing address updates to your invoice, please reach out to support@coda.io.
Related articles:
Overview of Workspaces
Workspace Members and Roles
Who is an admin and where can I view admin controls for my workspace?