Support interface layers wrong extruder

[Kulitorum]

I am trying to print this: https://grabcad.com/library/mobius-bicolor-1

On a three-way mixing extruder. Two extruders with colors (Red and white) and one with water-dissolvable innofill support material.

But the top "interface layers" of the support is printed with extruder 1 and not extruder 3 which holds the support material.

Is this me doing something wrong? You can see what I am talking about here: http://youtu.be/0XHwjVpYR0g

[Kulitorum]

My fault. I needed to pick the right extruder under "default extruder mappint" select extruder3 as interface extruder.

Fantastic slicer, love it.