I have the following particular situation in which I sent a customer’s invoice for 3 products by 200 each for Amount on the invoice a $600 but customer returned 1 product. now i need to create a credit note applied to invoice for 200.
if you are using the sale module you should use the wizard “Return Sale” on the sale you used to send the products to the customer. It will create a new sale with negative values. If you confirm this sale it will create a return shipment for you and a credit note.