four finger swipe not working

Hi there. I'm one of 2 users of a new mac air and have it set up to do the four finger swipe to hide windows and switch applications but I can't get it to work. The three fingers work when swiping to navigate and all the functions work on the other user of the computer (including the 4 finger manipulations). I have it set up the same in the settings as the other user so I can't figure out why it's not working for me. I haven't tried a reboot yet but will do that now. Just wondering what I'm missing here.

Thanks for any help