You can change the size of a slide in your PowerPoint presentation through the "Design" menu on the Windows PC, Apple MacOS, and web-based apps.

They are displayed horizontally, with slide numbers starting from one, but there are features in PowerPoint that allow the user to change the slide’s size and orientation.

To change your PowerPoint slideshow orientation from horizontal to portrait, you must access the "Slide Size" feature under the "Design" tab.

Use the Slide Master view in Microsoft PowerPoint to customize the look and feel of your slides and create a consistent view for your presentation. You may wish to create multiple master slides ...

Sometimes a presentation may need to be viewed in vertical or horizontal slides. PowerPoint calls these options Portrait and Landscape, and you can easily change the orientation from within the ...