Unfortunately, SCView is not able to directly modify a PO.
The PO must be updated in USAS. Once updated in USAS, you can get an immediately corrected PO pulled into the system. This is achieved by going to the Tools->Purchase Orders screen, right-clicking the affected PO, then choosing "Refresh PO from USAS".
A requisition with the incorrect PO number listed is also unable to be updated once it has successfully converted to a PO.
