Still not sure what you're trying to do.
The methods I know of communicating between apps seem to be QueryContent and Intent/Broadcast.
In DS QueryContent is a premium function (I'm not premium) but I think you want to change other apps settings, not just read them.
There's an intent that can open the Settings > Sound screen, so the user could change ring/notiifcation/media/alarm themselves.
null,null,"android.settings.SOUND_SETTINGS"
If you need to set the volume absolutely at the start of the media,
you can CreateMediaPlayer, then SetVolume (left and right), then SetFile.
If you have a control to set volume then you can save the settings and load them the next time the user starts the app.
Regards, ah