The Zoom feature can come in handy when the text or object you want to work with is too small for you to see. Zooming in on a slide makes it appear larger on screen; zooming out of a slide makes it appear smaller.
Click the Zoom In ( - ) or Zoom Out ( + ) buttons on the status bar.
You can also use the Zoom button on the View tab of the ribbon to open the Zoom dialog box and choose a new zoom level.
Click the View tab.
The Zoom group on the View tab of the ribbon includes a few more ways to control the zoom level.
Click Fit to Window.
The zoom level changes so that the entire slide is visible in the window.