To exchange items in the POS, we recommend that you click the "Find Ticket" button in the left menu and search for the original sale ticket. Once you've found it, click the "Return" button to start a return.
On the new return ticket, you will need to change the quantity of the item being returned to -1. Then, you will want to add the item the customer would like to buy in exchange to the ticket with a positive quantity.
See the below example for what this will look like:
If the prices of both items are the same, all you need to do is click the "Complete" button to complete the exchange. If the prices are different, the customer will either need to pay the difference or you will need to refund the difference to complete the exchange.