If write in an email address on an invoice/sales receipt for an existing customer. How can I automatically update the customers profile to include the new address?

Howdy, kevclark52. 

Thank you for reaching out to the Community. You can change or enter the customer's email address directly into the invoice when you create one for the customer. However, this will not automatically update in the customer profile.   

You need to edit the email address through the customer's profile, so once you create an invoice to the same customer, it will automatically populate the new email address. 

Please check out this article. This link contains multiple steps on how to manage your customers. Add and manage customers in QuickBooks Online.

I've got an additional article to help you beautify your sales form: Add, customise, or remove logos on sales forms.

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