Hi there,
QuickBooks Online is equipped to accommodate tons of different transaction types for your small business. You can enter a credit memo for your customer, or record a customer refund. If you've already closed your customer's current invoice, you can simply record this as a refund. I'll explain how to do that below.
This article will guide you through the steps for recording a customer refund based on various scenarios: Record a customer refund in QuickBooks Online. You can either record a refund for goods or services that didn’t satisfy the customer, or refund a customer's overpayment or credit.
If you've already created a credit memo, and now you have an unapplied payment, you may want to delete the progress you've made and follow the steps in the article instead.
I hope this helps get you back on the right track. If you have any other questions or if you need a hand with those steps, please don't hesitate to reach out to our tech support team.
Cheers.