How can I edit the email where I acknowledge receipt of payment on invoices? I can edit every other form, but there's nothing about this one email type.

Hello, @landisr.

Sending email in QuickBooks Online is a default set up. What you can do is when creating a Receive Payment you can manually edit the email from there. 

Here’s how.

1. Go to the Plus icon.
2. Select Receive Payments.
3. On the receive payment window, Select the Customer and the Invoice.
4. Click Save and send.
5. Then, update the Body of the email. Click Send and close.

You can also customize invoices to make it look personalize and appealing to your customers. Check out this article to guide you on how. Customize invoice emails.

Feel free to leave your comment below if you have any other questions. Keep safe.