You're right, @DBETHEA.

You can certainly go back to the overpayment and change it to Refund the Amount to the customer. Once you've updated the overpayment to that option, a follow-up screen will show refund payment options (Check, credit card, etc.). All you'll need to do is choose which payment option you'd like to send the refund from, then hit OK to save the changes. You can reference my screenshot below as an example. 

Thank you for sharing this idea with others on the thread. It's users like you that make having the QuickBooks Community so great. Sharing solutions is what helps us become a stronger team. Take care!