I could reproduce this strange volume problem on my carpc too.
If you tap on the +/- buttons then everything works normal.
If you hold down the + button so the volume rises a few percentages then it will auto-rise to 100%, click - button a few times and the volume starts to live its own life. Even closing centrafuse does not help the windows volume bars will go up/down all the time. Reboot fixed problem.
So tapping is the workaround till the bug is fixed.