If the default settings don't work for you , you can try this alternative approach.


<!-- Keybinding for Volume management -->

<keybind key="XF86AudioRaiseVolume">
<action name="Execute">
<command>pactl set-sink-volume 0 +10%</command>
</action>
</keybind>

<keybind key="XF86AudioLowerVolume">
<action name="Execute">
<command>pactl set-sink-volume 0 -- -10%</command>
</action>
</keybind>


<keybind key="XF86AudioLowerMute">
<action name="Execute">
<command>pactl set-sink-mute 0 1</command>
</action>
</keybind>


<keybind key="XF86AudioLowerUnMute">
<action name="Execute">
<command>pactl set-sink-mute 0 0</command>
</action>
</keybind>