Your currency is selected during the creation of your prepaid account..

If you want to pay with a different currency, you can

• create a new handle and pay from that handle. You can add the new handle as the billing contact if you don't want to do an ownership change on your domains.
• you can wait until your prepaid account is empty of funds, at which time change the currency in your “Billings options” page (in the Billing section of your account). Since you cannot change contacts for hosting products, this would be the only possibility if you need to change currency for renewing hosting products.

• create a prepaid account
• create a new handle