on the conform page there is a line of code that tells paypal what currency to use. this line of code will be different if you are using PayPal Standard, payPal Express Checkout or PayPal Direct Payments.
Your reply does not address the question that was asked:
Which paypal system are you using?
the code change that needs to be made will be different depending on your answer to that question. once you let me know which paypal system you are using, i will be able to direct you to the code that needs to be changed.
the available PayPal systems Are:
let me know which of these 2 systems you selected when running the checkout wizard.