The currency displayed in LTP is dependent on the Google Adwords account linked with Long Tail Pro.
Unfortunately, in AdWords, currently there is no option to change an account's currency. If you want to change the currency displayed in LTP, the only way to do so would be to create a new Adwords account that uses US$ (or your preferred currency) and then change the account that Long Tail Pro is linked to.
Creating a new Adwords account is free - you can find instructions here. Keep in mind that you'll need a new/different Gmail account in order to do this.
Also, please note that in some locations, the currency choices are limited by Google.
If you're having trouble with this, please contact our Support Staff here and we'll get back to you ASAP.