PurchEditLines ReceiveNow

Hello,

I'm very new to AX programming.  I've run into something that should seem relatively simple to solve but inexperience is getting in the way.

During purchase order receipt in the PurchEditLines form how would I set the ReceiveNow value to zero for each line in the PO?  Currently the ReceiveNow value is being set to PurchLine.PurchQty value.

Any help would be greatly appreciated!