You don't mention the version you are using.Unless you have a very old version, this is the easiest way:
- Instead of multiple text objects, create one multistate object. Use a shape, where the Normal state is 'invisible' because you set both Alpha and Stroke to 0. Add states with the text, one state for each text.
- Instead of show and hide when clicking a button, use the command 'Chang stae of... to'. That way old text will automatically disappear when another button is clicked.
BTW I have compared this solution with Hide and Show in two blog posts, one for non-responsive and one for responsive projects. They are in the eLearning portal.