In the PO, you go to the Returned Product list to return the product.
You can either scan the product barcode to increase the Returning field or fill in the field manually. Then you click on the Return button to return the product. Or you can click on Return All button to return all the remaining products in the PO.
→ The received product will be updated in the Returned Qty field. The product qty in your warehouse will also be updated (if the Stock Unit and Purchase Unit of the product are not the same, the system will automatically convert the qty, ex: returning 10 pallets (1 pallet = 20 units) will decrease the product qty on your source by 10 * 20 = 200 qty.
Also, each time you return the product, it will create a Goods Return Note in the PO.
You can click on it to see how many products were returned on that return.