Login to your Online Dashboard and click "Stores" in the left-side menu

Select the store you wish to edit

Under the "Store info", choose the desired store currency from the drop down

When you finish, click "Save" at the bottom of the page
Login to your Online Dashboard and click "Stores" in the left-side menu
Select the store you wish to edit
Under the "Store info", choose the desired store currency from the drop down
When you finish, click "Save" at the bottom of the page