Handling a partial refund on an item sale
If your transactions are changeable, you can redisplay the original invoice using the Sales Register window and make whatever changes are needed and record the transaction again. (Choosing changeable or unchangeable transactions) If the customer's paid for the items being returned, a customer credit will be created. Using the Sales Register, you can either print a refund check or apply the credit to another open sale for this customer.
If your transactions are unchangeable, you'll need to create a new invoice and enter negative amounts for the items being returned and a customer credit will be created. (To accept a partial return of items)