The Volume Slider 

        

Probably the less noticeable part of the user interface is the Volume slider. It is situated between the multi-purpose zone and the playback control buttons. It is used to compensate for different sound volume in separate clips. You can control it with the [+] and [–] numeric keys on your keyboard, or just by dragging the slider. Check the box under it to mute the output sound.

This Volume Slider is connected to the slider, situated in the Volume control window. If you move the slider from here, it is moved in the Volume Control window too.