Currency converter not working for some customers when currency bar is off

HI,
I’m using Version 2.1.22 of CURCY – Multi Currency for WooCommerce and I have set the default currency as Euro and set the countries and then all others to be in USD.

http://prntscr.com/c1pzu5ohlmki

My problem is that when I turn off the Currencies bar on the website some but not all of the USA customers see the prices in Euro. Here is an order example form a US customer but the prices are Euro:
http://prntscr.com/AM40Gt1zz-aF

but I see other US orders and they are in dollar? Can you see why this might happen? I have checked the 2 customers reported today and both have billing and shipping addresses in as USA.

Thanks
Breda