I am having this issue with my store. Recently I installed an app for store currency conversion. The app worked fine when I change to another country. But the issue is when I select any product with other variants the currency changes to USD again. Which will be confusing for my customer if he wants to buy my store items in his local currency. I will charge him for his purchase in USD. But store currency should work if he wants to check the item price in his currency.
Please check my store item link below
When you select other variant currency changes to USD
https://www.shopforgamers.com/products/graffiti-cover-case-for-ps4-controller