Req currency does not flow to PO

 Why are there so few PeopleSoft communities.  Would think there would be one per module. 

Real question:  My end users want the PO currency to be the same as the req that it is created from.  Example:  Req is entered in USD (Transaction currency, the base currency is CAD) for a Canadian company.  When the PO is created, it has a transaction and base currency of CAD.  Users want PO currency to remain the same as it is on the Req.  How can we override this?