Hello.
This solution has worked in the previous versions of Dolphin.
I guess it will also work in the new versions, too.
CHANGE CURRENCY
1) Run this query in phpMyAdmin (XXX stands for the three-letter currency code of your preferred currency)
UPDATE `sys_options` SET `AvailableValues`='AUD,CAD,EUR,GBP,USD,YEN,XXX' WHERE `Name`='pmt_default_currency_code';
2) Clear database cache in Admin Panel -> Tools -> Cache -> Clear Cache: DB
3) Go to Admin Panel -> Modules -> Payment -> in the Payment Settings block change the currency code to the one you have just inserted, change the currency sign's HTML code to the code of your currency (you can find some codes here http://character-code.com/currency-html-codes.php)