When I click on the Payor View, it shows "Merchant Details" and my account email address. How can I modify this merchant email address to make it my billing email?

Nice to see you here, @Aaron-bid. I see that every business has different ways to communicate with their customers. I've got an easy resolution to help you change the email displayed on your invoices.

The merchant email address on the sales form is the Customer-facing one. To update it to your billing email address, let's go to Account and Settings by following the steps below:

1. Go to the Gear icon at the upper right corner, then choose Account and Settings.
2. Select the Company tab and go to the Contact info section.
3. Make sure to deselect the Same as the company email to show a field where you can enter the new address.
4. Hit Save and Done.

After that, create a sample invoice to see if the changes apply to your invoices. Just press the Print or Preview tab on the bottom part and check the email. I'm adding a screenshot below for reference:

For more details, check out this article: Change your customer-facing email address. 

Feel easy to open these links about personalizing sales forms and managing invoice payments:

• Customize invoices, estimates, and sales receipts in QuickBooks
• Record invoice payments in QuickBooks Online

You can always leave a comment below if you have follow-up questions about modifying email addresses. Looking forward to working with you again. Have a great day.