What setting(s) does one change to allow the supplier’s currency to be currency on the payables invo

I hope someone in the Payables community can answer the following question.

 

We have an operating unit where the ledger currency is USD (US dollars).  When suppliers are added to the Payables vendor master, they are setup with a preferred or functional currency. 

  

Example, let say we have a German supplier who wants to be paid in EURO.  This supplier’s vendor master record is setup with EUR as the functional currency.   When the Payables user enters an invoice, the user wants the system to automatically set the invoice currency to be EUR--from the vendor master.  Currently, the invoice workbench sets the invoice currency to the ledger currency, USD.  The user must manually select the currency, EUR, for the supplier.