You can edit customer details on the Customers page, @nat25.
Here’s how:
- Navigate to the left navigation panel and click on Customers & Leads.
- In the Customers section, find and select the specific customer whose details you want to update.
- Click the Edit button and modify the email address.
- Input any additional necessary information and click Save.

If you’re unable to save the changes, try refreshing your browser or logging out and back into QBO. Then, attempt to save the updates again.
You can also refer to this article to learn how to sort and manage your customer information in QBO: Manage customer information in QuickBooks.
Please let us know if you have any other concerns.