Delivery cost invoice based on new material price
I have a case where PO was created with material price say 100 USD and delivery cost condition is set as 3% of material price so PO was created with delivery cost value as 3 USD. Then we have posted invoice for PO based on material price of 100 USD. Later we changed material price to 150 USD and posted GR, GR is posted correctly with old PO price but when we are trying to post invoice for delivery cost invoice is picking delivery cost as 3% of 150 USD not the old PO price. We want system to post delivery cost based on PO price not on current price.
Can anyone help if there is any setting which can allow to post delivery cost invoice with old price.
Thanks in advance.