help with Multi Currency: it keeps changing currency when customers choose different shipping options

Hi There
I am having trouble with the multi currency plugin in my woo commerce shop. It has many currencies for customers to select from. However when they go to the check out page and select their location for delivery or even a delivery option, it always changes the currency to $USD. This is causing confusion for them. I would like it to stay in the currency they have chosen and allow them to change their location or choose a delivery option.