var curr_song;
...
curr_song=media_play(...song in current level...);
...
//somewhere in your code:
media_stop(curr_song);
level_load(...next level....);
wait(3);
curr_song=media_play(...song in next level...);


am i right?? and can i put this in main function

media_stop(curr_song);
level_load(...next level....);
wait(3);
curr_song=media_play(...song in next level...);

Thanks very much