How to modify a receipt route code in a purchase order

Hi,

I'm facing a problem when I need to change a receipt routing code in a purchase order which has been booked in the system.

For this purchase order, the default receipt route code is coming from the set up "Default locations and printer" P400951.

I need to change the receipt routing code in the header and in all lines, and I don't see hox to do .

Thanks for your help

Regis