PowerPoint Text Change Upon Click
Trigger animations should do it. Here's how.
Duplicate the Fruit 1 text box, change the text to Apple.Move the Apple text box exactly atop Fruit 1 and make sure that it's at least a bit wider than Fruit 1.
Give Apple's shape a fill of Slide Background.Now add an appear animation to Apple then in the animation pane, timing effects, set it to appear on trigger when you click Fruit 1.
Test to make sure this works right. Finally, select both text shapes and press Ctrl+D to duplicate them as many times as needed. Change the text in the dupes to Fruit 2/Banana etc. They'll retain the animation so you don't need to go through all those steps for each of 'em.
[Dusts off hands] My work on this planet is done.