The Preferences Tool allows you to adjust general settings in the Mars Simulation Project.
Adjust the sound volume of the user interface with the volume slider.
The 'Mute' checkbox will mute the user interface regardless of the slider setting. This makes Mars Simulation output no sound to your sound output device.
The 'Show Unit Toolbar' checkbox will toggle between showing and hiding the toolbar with open unit windows at the bottom of the main window.
The 'Show Toolbar' checkbox will toggle between showing and hiding the toolbar with commands at the top of the main window.