Currency returns to the default value on another page

Hi there,

I have two currencies on website: USD (default) and EUR. If I choose EUR and go to another page, there is USD (default) again. This process repeats until I put something to Cart.

After that (even if I remove Cart) everything works correctly. It means if I choose EUR, everything is in EUR, on all pages, until I change it to USD.

Any ideas, what can be wrong?

Thanks
Tomas