If a customer or vendor has no transactions, you can change the currency assigned to that customer or vendor.
Why can't I select a different currency?
What should I do if I can't change the currency?
To do this task
Click Customer Center or Vendor Center.
On the Customers & Jobs or Vendors tab, double-click the customer or vendor whose currency you want to change.
Select the new currency from the Currency drop-down list and click OK.