I did not see a trigger for the text box. But, you cannot select parts of text to jump to a slide or show a layer. You can highlight parts of text and open a file or jump to a URL. That said, the easiest way is to create a shape that coves the text you want users to click. In the shape properties, make the shape 100% transparent. Do not select "No Fill" as this will not work. Then remove the outline for the shape. Create trigger for the shapes to either jump to a slide or open a layer.
In the attached file, I left the outline of the shapes so you can see them.