Hi there! To make it easier for you, I highly recommend you using this free app Currency Converter, this app will automatically find your customer's location and show the corresponding currency. Show both the original price and the converted price as the customer's request. Convert the price of products in 164+ currencies. Hope this will help, happy selling!
Nick here from Shopify.
You are able to change the currency from your store if you wish. This is something you would need to contact the support team directly to do. Only after you have launched your store and have made sales, can you make the change. You can contact Shopify Support here to change your store currency.
You can see the help guide Shopify has about this here.