If you want to continue highlighting multiple pieces of non-contiguous text, simply click the highlight button without selecting any text. You'll see ... in PowerPoint by inserting a shape 3.

How to use color in a PowerPoint ... Figure A Figure B To see the highlight at work, press F5 and click the slide. Press Esc to return to Normal view. You can use any shape and any color–you ...

Highlighting ... you have to sign up through TestFlight. Unfortunately, the beta for PowerPoint is full. You can check Microsoft's Office Insider app page to see which ones have openings.