Shopify Plus only
Selling in multiple currencies is a feature for stores on the Shopify Plus plan only. Read more about multi-currency on Shopify.
If your Shopify store is selling in multiple currencies using Shopify Plus' multi-currency feature, Order Printer Pro will automatically display all amounts using the customers currency.
No changes are needed to the templates, they will automatically detect which currency the customer used, and display the amounts correctly.
Unfortunately it is not possible to display amounts in the order currency, if you are using a third-party app to add multi-currency to your store. They unfortunately do not add enough information to orders to make this possible.