If you want to change your view, you likely go to the View ribbon. If you want to start your presentation you likely go to the Slide Show ribbon but there’s a quicker way. Look to the bottom right of the PowerPoint window and you’ll see this little bar.
This first option expands the Notes section so you can start writing.
This button may not appear based if you’re only using one monitor. It refers to screen optimization.
Normal view, slide menu on the left side, notes optional on the bottom, and your presentation in the largest part of the window.
Slide Sorter displays all your slides in the middle window so you can move them around while viewing at as larger boxes than the normal left side menu view.
Reading View lets you see your slides full screen similar to a slide show. You can change the display back to Normal or press escape to return to the last view choice.
Start your Slide Show with one click by pressing this button. The show will start on the current slide.
You could use Ctrl + Scroll Wheel to change your zoom setting or use this handy toolbar to zoom in and out.
This number is the current zoom setting.
Fit slide to current window does what it says. It changes the zoom setting to expand or contract the slide to fit.
Ryn Nicol 