When a customer returns items, you may do it from Sales > Returns. It is very important that the order be shipped so that the return is done on the items and relate order. 

Dashboard > Sell

Returns

Select Customer

Select item

Select order - the returned itms should be related to the order selected 

Select > Quantity to return

Touch the basket

Touch the return icon

Finish Return - keep in mind that if you do not type any Amount to return now, it will be available on the customer account as a credit which will be available when you pay an invoice from the customer on the payment metod menu 

Or Finish Return > Type amount to return now > Save 

Return finished 

Send icon - allows to E-mail, View and Print the return

Minus-circled icon - allows to Void or Delete the return

Touch SelBuk logo > Main Menu > Database 

Database > Sales / Invoices

Touch > Returns 

List of returns made