...
Navigate to Control Table → System Defaults → Accounts Payable
Change the Re-instate Order when Invoice deleted dropdown menu to one of three values:
Fix = Fix and reinstate the PO line amounts automatically when an invoice is deleted. Any amounts transferred into the Invoice you are deleting will be reinstated in the PO.
Ask user = Prompt the user if they want to reinstate the PO amounts when they delete an invoice.
Don’t Fix = Don’t reinstate the PO amounts when an invoice is deleted.
...