Click the site you want to edit from the sites table, after that the button with the 3 points (...) should be available to press. Press the button and select Payment Gateways.
You will be redirected to the page of Payment Gateways, where initially Paypal and 2Checkout are created.
From the plus sign you can add more by selecting one Payment Gateway from the table or you can modify them. The options for each Payment Gateway are:
Is Active - if the payment gateway can be used by users to pay for the services, if it is not active, it will not be visible to your users.
Is Default - you always need a default payment gateway in case all others are inactive.
Collect VAT - if applicable, VAT will be added to the order amount, only for users who are in the EU, VAT compliant with each country's legislation.
When using Webmoney Bitcoin, the order is calculated in dollars and after that is transformed in WMX. WMX is related to the bitcoin value. Your earnings from that order can have less or greater value than the money made on that order because the bitcoin value is volatile.