Purchase Order Currencies - how to add Dollar currency?

When generating a Purchase Order, the dropdown box is present to select the currency but it only displays GBP, CHF (swiss) and Euro’s. I have USD activated but in the currencies settings, but it still doesn’t show up.

Is there a way to get USD to be present in that drop down as well?
Any assistance would be greatly appreciated
thanks

you can choose $ for single Thirdparties when you create them. maybe that will work

hi I have solved my using multi currency module