How to set Appointments+ currency to Roubles

I want to use Appointments+ without collecting payments for now.
Is it possible to set currency to Roubles somehow (PayPal collects roubles for now, by the way, I had a letter from them recently )

In the future I would like to cillect payments , but I need to integrate a new payment gateway to Marketpress. Is there a guide about this? I am newby and kind of lost here in all this information