Not possible to switch shipping price

Hello,
I have a simple one-product site ( https://www.xlifter.com ). I use fixed prices. It works for products. Premium plugin.
However, there is no option to change – define the shipping currency.
The result is that the product price + shipping price is shown correctly in default (EUR) currency.
However, in the secondary currency (CZK), the shipping price is shown in the default currency with secondary currency symbol, which totally doesn’t make sense.

Please advice.

Thank you,
Jan