Currently Event Espresso does not support multiple currencies, all of your events will use the currency set for your country set within Event Espresso -> General Settings.
We previously had a similar question to this and posted an explanation and possible work around (using WordPress Multisite) here:
The support post ‘Setting event price in Canadian Currency’ is closed to new replies.
Have a question about this support post? Create a new support post in our support forums and include a link to this existing support post so we can help you.
Support forum for Event Espresso 3 and Event Espresso 4.