This Feature used when you dont give permission for your cashier for add discount and retur item. However you can give a key for their when needed. One key only use one time, and you can set expired date key according to what you need
1. Go to Setup - more menu - application Configuration - POS -Authorization Key - choose Generated and fill key digit you need
2. Promotion - Tab "Generate" - Choose Discount or Retur
3.You can see result that has been made by generate key in " Promotion -Tab 'Unused' "
4.SELL - Full screen - Query Configuration - Input Password "use one of the keys Promotion" Example I use key 345493 - OK
5. Menu Promotion - Tab "Used" will be see key 345493