1. Go to the Customers tab.
  2. Search for the billing customer and click on the edit option.

    Now you will be directed to a new page where you will be able to see all the details for the billing customer.

3. Now click on the edit option as shown in the image below.

A pop-up would appear and you can update the primary contact details and address in the first tab.

4. There are sub-tabs in which you can click to update/edit the billing notes, additional contact details, and attachments.

5. Click on Save and the details for the billing customer would be updated.