Trouble with triggers...

I know what I am trying to accomplish is easy so this is maddening. I would simply like for the user to click on the buttons (left) to see a description in the gray box (right.) I did this easily in PowerPoint with triggers and stacking grouped shapes w. text boxes on top of each other. When I tried to recreate this in Articulate it didn't work because the text remained even if the shape "gray box" was hidden by a trigger (even when grouped.)

Then I started thinking this might be a layer situation but I'm still pretty knew and could really figure out how to only hide one object in layers.

Essentially I just want the gray area to show corresponding text triggered by the user clicking on a button.

I've included a screen shot.