How to update Ubuntu scroll speed

It is very strange that you are not provided a default GUI to update scroll speed on Ubuntu, it's one of the more obvious configuration options that are missing.

We're going to use imwheel to adjust the scroll speed of different applications.

First create the config file:

touch ~/.imwheelrc

vim ~/.imwheelrc

And paste the following config in:

"^google-chrome$"
  None, Up, Button4, 4
  None, Down, Button5, 4
  Shift_L,   Up,    Shift_L|Button4, 4
  Shift_L,   Down,  Shift_L|Button5, 4
  Control_L, Up,    Control_L|Button4
  Control_L, Down,  Control_L|Button5

The `"^google-chrome$" part is the application for which we want to update the scroll speed. In order to get the name of an application you have to enter a bash command:

xprop WM_CLASS | grep -o '"[^"]*"' | head -n 1

And then click on the application, the name will be displayed in your terminal.

In the above configuration Button4 is scrolling up and Button5 is scrolling down.

To change the scroll speed, edit the number after the comma on the lines starting with None, in our case it is 4 for both scrolling up and scrolling down.

Save the configuration file and install imwheel:

sudo apt install imwheel

Now start imwheel:

imwheel -b "4 5"

If imwheel was already running on your machine you might have to stop the process before starting it:

killall imwheel
imwheel -b "4 5"

The reason we pass in the -b "4 5" flag is we only want to target specific buttons on the mouse, otherwise it blocks your mouse's side buttons (back, forth, etc).

Every time you edit your ~/.imwheelrc you have to rerun the commands:

killall imwheel
imwheel -b "4 5"

If you don't want fine grained control with different scroll speed for different applications you could set the scroll speed for all applications, with config similar to this

".*"
None, Up, Button4, 4
None, Down, Button5, 4
Shift_L,   Up,    Shift_L|Button4, 4
Shift_L,   Down,  Shift_L|Button5, 4
Control_L, Up,    Control_L|Button4
Control_L, Down,  Control_L|Button5