It's due to the sound settings in the "volume slider" Startbutton mod.
You can edit the xml to a prefered sound volume or use the push button version that I provide as the default.
FYI
The Feature details also state this.
Lots of information there, just click the "..." button next to each feature for a screenshot including details about the feature and how to use it.
Quote from feature page:
Note: The "Slider" version loads the preset volume settings within the xml at UI load. So if you wish to save your own volume settings I recommend you use my push button version instead. ;-)