Hi, Artur1970!
In order to activate the butterfly-function you need to assign Quer+ (ail+) to the outer servos and flap+ to the inner servos of a 4-servoed-wing. The elevator-servo should be assingned to Höhe+ (elev+). (In case of a V-tail ruder and elevator should be assigned to V-tail+.)
With the mc4000 it is necessary to set the different ratios for Quer, Flap and Spoiler (ail, flap and spoiler) for each wing-servo. This is improved with the ROYAL and PTX!
Essential for butterfly is the spoiler-ratio an all servos! Mind the compensation of the elevator! Here it is the spoiler-ratio again that you should set to about 5 - 10 % for a start.
You are free to assign the stick-functions as you like it. But I would recommend to give the spoiler-function to the gas-stick. You can use the brake (butterfly) more sensitively - but you have to assign a possible motor to a switch.
Moreover you can set the spoiler-ratio in different flightphases to different fixed values! This enables you to activate butterfly with just one flip of a switch.
with regards
profimc