I have been asked over the last few months the same question.
How can I change my default currency so I am not charged extra fees during conversion rates by my payment gateway / bank provider?
The answer is very simple, with every site made with SocialEngine a lot of people use the system to have subscriptions to gain access to different sections of the site but never change the Default Currency within the program.
If you keep the currency as US Dollars you could lose money when you exchange it to your own currency.
It is very easy to make your preferred currency the default one.
Go to your Admin Panel
Select Billing and click on Settings.
I currently use Advanced Payment which allows me extra gateways but the same layouts and currency’s are there.
You can now use the dropdown to select your default currency. Once you have saved the changes all new payments will now be processed as that currency.
No more having to exchange from US Dollars to GBP and so on (Potentially saving you a fortune)!