Hello craig7126,
Thanks for reaching out in the Community. I'll be happy to show you how to edit the receipt body in QuickBooks.
In order to make the edit in question, you'll have to navigate through the Custom Form Styles menu. To do this, click on the Gear icon > Custom Form Styles > click on the Sales receipt template > navigate to the Emails tab > from here you can make the necessary changes to the email body of your sales receipt. Once you're done, make sure you save your changes.
From here you'll be able to use the updated template when creating a sales receipt. Give this a try and let me know how you make out. I'll be a message away in case you need anything else.