will stop all sounds in the movie.
button sound is just putting the sound on the appropriate keyframe in the button.
Object sound takes a bit of actionscript. You need to create a new sound object and then depending on how you want to load it..... either attaching it from the library or using the loadSound method...
This would require the sound to be in your library and exported for actionscript in the first frame with an export name of "soundtrack"
mySound = newSound();
trace("Soundtrack is " + mySound.duration/1000 + " seconds in length");
Here is a very nice sound tutorial.......