not working

Hi .
The currencies are not changing automaticity to the country where people are viewing my website., I lost a customer last week over it along with him are saying that he had tried to do it by clicking on the currency on the sidebar did not change. I tried it took a few attempts for it to switch currency. The euro currency is coming up un thousand instead of hundreds, Can you help I am not good at websites if you could check to see if changed something woo-multi-currency that I should have not done. Take care keep safe,
Cheers
Tom