AmbientSound of selected waterplane can't be selected. Just the underwater sound plays

Hello,

I have again a new question regarding to the waterplane, which I yesterday used to create different atmospheres for my extraterrestial landscapes (Mars, Venus, etc.). Everything seems to work fine, except the palying ambient sound, which is the underwater sound.
I can't select a different sound, even dozens of sounds are selectable under AmbientSound in the waterplane object and I even if I can select a different sound - the underwater sound still cotinues to play.

Why is this happening?

Yours sincerely
Superneutrino

 

Or can you even disable the underwater sound with LuaTriggers?