There are a few different ways to do this:
If the "textbox" you are talking about is a dynamic textbox, then to modify the text in the box, simply put te following command on the button.
on (release) {
variable = "your text here"
}
The text can have html tags if the dynamic text box has html selected.
Another way is to double click the button to modify it, add a new layer to it, select the over frame and insert a keyframe (f6) now in this keyframe, put the text wherever you want it.
A third way is to create a movie clip with any text and animations you want to appear on mouseover. Then edit the button (double-click) and in the over frame add the movieclip where you want it on the stage.
If this isn't clear, or you can't get it working, post again.
Hope This Helps! Lumstar
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