|Buyer Edit Option|
If you select this option, buyers will be able to edit their payment total to account for additional charges or discounts that you weren't able to specify up front (for example, extra shipping charges).
You might use this option if:
If you choose to allow buyers to edit their payment total, be sure to specify clear payment instructions. These will be shown to buyers when they review their purchase. Buyers can pay you faster because they don't have to request the total from you. If a buyer pays too little, you can ask him or her to pay the additional amount through any payment method.
Note: A buyer is always allowed to edit the payment total if: