Change 1 button, save, close game. It will create file "Custom.binding" - links above show where to find it. It is text XML file, open in notepad and just edit as u like - put needed keys, save, run game.
Now, one more torture : I don't find the links showing where I can find the file "Custom.binding" ... This is hell, I told you ! I did everything you said : I changed 1 key, I saved, I closed the game ... and nothing.