Hello Audrey26,
Welcome to the Community page,
Here are the steps you need to do to record the refund for your customer
1. go to the + icon create expense
2. select customer, the date the money left your account and expense from the debtors account save and close
3.go back to the + icon, select credit note, fill in the customer name and amount save
4. go to sales on the left side navigation bar, click on customers at the top of your screen and find the appropriate customer
5.clcik new transaction on the top right of your screen and select payment
6.on the next screen tick the expense and credit note (make sure no other transactions are ticked- save and close) this will show the customer refund to then match up.