To enable multiple currencies first you have to go to "Admin" from the side menu in Ewity

Then go to sales under the "Settings" from the drop down menu under "Admin"

Under "Settings" go to "Sales" and scroll down till you find "Bill in other currencies?" and "Enable Other Currencies"

Press "Add New" and enter the currency code and the appropriate exchange rate for the currency and select default if you wish to enable the currency as a default currency