Futaba it is!
Ahhhhhh on Futaba if you decrease sensitivity on a control you are entering NEGATIVE Expo. (from this perspective you are REDUCING control sensitivity around neutral so it is NEGATIVE.)
On JR and Spektrum if you do exactly the same thing you are entering POSITIVE Expo. (Positive because from their perspective you are ADDING something which is POSITIVE.)
Both manufacturers are correct in their statements. It depends on the chosen perspective as to whether it is positive or negative..
Clearer now ???