Hello, marcdy.

I'd like to share some details about customer refunds.

You can create a credit memo and choose how you want to handle the credit (Retain as an available credit, Give a refund, or Apply to an invoice). 

Here's how:

1. Go to Customers > Create Credit Memos/Refunds.
2. From the Customer:Job drop-down, select your customer.
3. Enter the items you're giving a credit for.
4. In the Main menu, select either Use credit to give refund or Use credit to apply to invoice. 
5. Follow the on-screen instructions.
6. Click Save & Close.

I've got this sample screenshot for a visual reference:

For more information about the process, you can read this article: Give your customer a credit or refund in QuickBooks Desktop for Windows.

Please let me know if you need anything else. I'll be right here to help you out some more. Take care!