I was wondering how to make my touchpad settings permanent in Ubuntu. I could find a few pointers on the net, like:

But sometimes it makes sense to look at your own system’s documentation:

% cd /usr/share/X11/xorg.conf.d
% head 50-synaptics.conf
# Example xorg.conf.d snippet that assigns the touchpad driver
# to all touchpads. See xorg.conf.d(5) for more information on
# InputClass.
# DO NOT EDIT THIS FILE, your distribution will likely overwrite
# it when updating. Copy (and rename) this file into
# /etc/X11/xorg.conf.d first.
# Additional options may be added in the form of
#   Option "OptionName" "value"
Section "InputClass"

Which seems pretty obvious to me. I added

Option "TabButton2" "3"
Option "TabButton3" "2"

as my personal configuration.