How can I configure my mouse side buttons to control volume

Install

sudo apt-get install xbindkeys xdotool

Create a a default ~/.xbindkeysrc

xbindkeys -d > ~/.xbindkeysrc

In the ~/.xbindkeysrc, add these lines:

# Adjust volume with mouse buttons
"xdotool key XF86AudioLowerVolume"
    b:8
"xdotool key XF86AudioRaiseVolume"
    b:9

Start xbindkeys

xbindkeys

The buttons will now adjust volume

In Startup Applications, add an entry to autostart xbindkeys on login:

• Name: xbindkeys
• Command: xbindkeys_autostart