The currency issue is actually not directly related to the theme, but due to your broader Shopify platform’s ‘Admin > Settings’ set-up.
As a first step, we would advise that you check your ‘Shopify Payments’ settings, as the issue you have mentioned depends on which currencies you accept in your store. For context, Shopify Payments allows you to have multi-currencies at checkout, but it isn’t a payment provider in all geographic locations. So what happens is that your storefront has to use your store’s default currency (from your Admin > Settings) if your store doesn’t support the country in the list.
So you will need to either add the ‘missing’ currency to your list or remove it from the Shopify Market. For more information on this process, Shopify should be able to help you, as our theme has no impact on this. Shopify have 24/7 support which you can reach by clicking the link here: https://help.shopify.com/en/questions#/login