Change cursor speed in libinput

You can set the cursor speed in two ways:

1. Set an option in /usr/share/X11/xorg.conf.d/40-libinput.conf

On original 16.04, or 16.04.2 stack it is 90-libinput.conf.

The option is called "AccelSpeed". It is a float number between -1 and 1.

Example:

Option "AccelSpeed" "-0.5"

will make cursor slower.

2. To test setting before you set it in the conf file you can use xinput command. Run it this way:

   xinput set-prop ID "libinput Accel Speed" -0.5
   

The ID is your touchpad ID in xinput output.

You can check props by

xinput list-props ID

The xinput setting is not persistent and will be reset after a reboot.

Note: The option in xinput is with space Accel Speed and there is no space in the conf file option AccelSpeed.

If you want to see what are other settings, refer to this manual:

http://manpages.ubuntu.com/manpages/zesty/man4/libinput.4.html

In addition to the response above, I would recommend you configure these via a config file in /etc to avoid having your changes overridden by an Xorg update. One of the paths Xorg is looking for files is /etc/X11/xorg.conf.d/. Simply add a new conf file in there. These load alphabetically, so make sure your file is called something like z-touchpad.conf to have your changes applied for sure.