You can set the respective trading charges here.
Commission - you can set the commission value here. If you want to change then type of the commission, please open the
Instrument Editor dialog window.
Slippage - if you are trading on a dynamic market, the current rate can change between the time of sending an order to a broker and the time of receiving it. In that case, the broker sends back an enquiry as to whether you accept the new price. If this is often the case, you can set a few pips slippage. Forex Strategy Builder accrues this slippage both, when you open and close a position.
More button opens the Instrument Editor window, where additional options are available. For example, the number of digits and the lot size parameters can be set there.