The issue I have with this response is that QB NEVER asks me if I want to create a credit memo. I'm trying to create a credit memo from the unapplied overpayments on a customers account, but does not give me an option to connect the over payment to the credit memo. If I enter the amount of the overpayment QB duplicates the credit. The best way I've found to deal with it is to create the credit memo, then delete it when the customer applies the credit to a future invoice. It's the only way to NOT allow QB to duplicate the credit. It's ridiculously wonky. 

Back to the original question, How do I create a credit memo for a customer from an overpayment?