Hey @MyCity ,
In my experience, the best way to get app issues resolved is by reaching out to the app developers directly. They are the best equipped to handle issues that crop up. Check out our guide on finding support for your app here.
It’s important to note that Shopify doesn’t allow developers to convert prices on the Checkout page, so the app you installed would provide a workaround such as a custom message on the cart page or if they hover over the converted prices, they’ll be able to still see the original prices.
Merchants like yourself can enable selling in multiple currencies with Shopify Payments, and multiple languages. This means that customers can browse the shop, and checkout, in their preferred currency and/or language.
Otherwise, have you heard about Shopify Markets? It’s a cross-border management tool that helps you identify, set up, launch, optimize, and manage your international markets - all from a single store. When you sell to markets, your customers can view prices in your store, pay for their orders at checkout, and receive refunds in their local currency. By default, prices are converted automatically using the current market exchange rate, but you can set exchange rates manually.
You can find out more below: