PeopleSoft Payables 9.2.34 - How to override Discount Amount and Discount Due Date?

Navigation: Accounts Payable / Regular Voucher Entry / Payments tab

The Payment Terms is correctly calculating the Due Dates, but the Vendor is offering a random varied Cash Discount if paid by a certain date. The fields "Discount Amount, Net Due Date, Discount Due Date and Accounting Date" are all greyed out.

Is there a security setting somewhere that will allow these fields to be opened up so the AP Associate can manually enter the cash discounts and discount due dates? Or is there another way to enter non-percentage-based/non-static-amount discounts? Thank you.

-tam