Hi pcmxa,
Left click on the speaker icon in the notification area of the taskbar (where the clock is situated) to bring up the master volume control. At the bottom is an option 'Mixer'. Click this, and all current applications running will have their own individual volume control available, as well as the master volume control and that for Windows Sounds. Each application can be separately controlled and muted from this panel. Of course, the settings on the master volume control affect everything else, and selecting mute here will mute everything else as well.
Dwarf