Movie clip rollout

I'm sorry but if i keep onRollOut on the movieClip, when i'm over someone button, flash detects this action like a rollOut for the movieClip.

Keep your onRollOut for the movieClip, but add a onPress. In this onPress you hitTest for the three buttons, and perform the necessary actions that so far are on your buttons.
If you want the buttons to react visually, you need to change them into movieClips, and remote control them from the parent movieClip's onPress and onRelease handler (e.g. button1_mc.gotoAndStop(2))

When you assign a mouse event method to a movieClip you can no longer use mouse event methods for all it's child objects (stuff inside it).
Work around:
Place another movieClip inside your current movieClip, send it to the back (or so that it is behind all the buttons you want to use) and make it large enough so that it its edges expanding over the whole movieClip ( I normally use the movieClip background to do this, but you can use a solid fill movieClip and just set it's alpha to zero if you like).
Add the onRollOut events to this new movieClip.
Use _parent.gotoAndPlay(1); to send the initial movieClip to frame 1.
Because the buttons are no longer child objects of the movieClip your using to detect onRollOut they will retain their mouse event functions.
So your setup is like this:

Your movieClip contains ---> (detectorMovieClip, yourbutton1, your button2 .....)

Hope that all makes sense!