Method #1: Alsamixer
- Run #alsamixer in console
A graphical-ish program comes up...
Left & Right arrows - Select the sound channel (Master, PCM, etc)
Up & Down arrows - change volume of that channel
M - Mute/Unmute that channel (Muted channels will have an 'M' at the base of the volume slider.
Esc - Exit (changes are saved)
- Right click sound icon in tray
Select "Config Window"
"Retrovol - Configuration" window will show...
Select "Hardware" tab
Make sure "Master Playback Volume" is shown under "Active Sliders" (if not, select it from "Inactive Sliders" and click the left arrow button).
Click Apply
- Right click sound icon in tray
Select "Full Window"
Check/Uncheck the "Master" box