does any one know how enable it ,so sound doesn't stop when i'm in a 2d panel?

Try this onehttp://virtualfsx.wordpress.com/2011/08/02/switching-to-another-window-loses-fsxsound/

i don't have a creative sound card and i don't have this problem in any other aircraft.. what's next? i should also mention that my 2d panels are on separate monitors, so i am clicking completely away from a VC or regular cockpit.

You are clicking on a window pane which does not have sound from the application ( fsx). Show stopper with on board sound.