To turn on and off or change your sounds go to the Toolbar above in Dasher. Click on the Settings icon and choose the Sounds tab. (Or: Menu above: Edit > Settings > SoundsTab)
Select one of the sounds by clicking on it. It then appears on the bottom with the option of a drop down list for sounds. You can add others too to that. On top in the list is 'none' to mute the sound.
On the right you find a slide to control the volume. Below it you find a 'mute' option to mute all sounds.
Move sounds are not in this list. They are controlled by a variable named 'bell'.
Type on the command bar under the Main Tab of your Channels Console: set bell 0 .. to hear no moves.
Type: set bell 1 .. to hear moves in your own game and games you observe.
Type: set bell 2 .. to only hear moves from your opponent in your own game.
Type: vars .. to see your variables.