Hi there, @RetiredLF.
Let me guide you on how to enter a credit memo in QuickBooks Desktop.
Then you have to record the refunded amount:
For additional reference, you can check this article: Record a vendor refund in QuickBooks Desktop.
On the other hand, you can also check this link for your future reference about QuickBooks Desktop: Help articles for QuickBooks Desktop.
Please let me know if there's anything you need when applying customer credits, please don't hesitate to leave a comment below. Keep safe always.