I want to konw how to display object B with sound BB after object A with sound AA.

That is , the object B with sound BB will be display after the object B and sound BB.

One more Question: What is and where is "End of Media" action?

1. You can attach sound file directly to the object (see Object Properties dialog - Sound tab). In this case attached sound will start when the object appears and stops when it becomes invisible. If you want the objects narration to be played in full - set delay on the second object display exactly (or a little bit more) than first object's sound duration. The best way to do that visually is Timeline panel.
2. End Of Media is not an action - it is event of Video object. Though you can play audio files too with this object. In this case you may also use Invisible mode of Video object.

This one I can do, but what if I want to PAUSE the whole frame using FRAME NAVIGATOR? The animation or object movement based on the timeline pauses, but the sounds attached to the object just continues to play.
Is there a way to pause both the animation and the sound at the same time using just one button?