When you create a new presentation in Microsoft PowerPoint, by default, all of the slides are in landscape orientation. If the material you plan to present looks better in portrait orientation, you can easily change the it. But with PowerPoint, it's an all or nothing proposition; in order to change one slide to portrait mode, you have to change them all. If you want to change the orientation of only a few slides, there is a workaround, but it requires a little effort. You must create a second file to hold the portrait slides, and then link the two presentations.
Change All Slides to Portrait
Select the "Design" tab and click the "Slide Size" icon in the Customize group.
Select "Customize Slide Size," and then select "Portrait" for the Slides setting. Click "OK."
Select "Maximize" in the pop-up menu to keep all of your text and graphics the original size. If you select this option, you may need to rearrange some of the elements so that they fit on the page. If you prefer to shrink the text and graphics so that they fit in the width of the new slide shape without requiring any rearranging, select "Ensure Fit" instead.
Change Individual Slides
Click "File," "New" and then "Blank Presentation" to create a PowerPoint presentation in a new window.
Select the thumbnail of the slide that you want to change, and then drag and drop it into the new window. PowerPoint creates a copy of the slide. Repeat for any other individual slides you want to change to portrait orientation.
Change the orientation of the presentation in the new window. Select the "Design" tab, click the "Slide Size" icon, select "Customize Slide Size," and then select "Portrait" for the Slides setting. Click "OK" and then select either "Maximize" or "Ensure Fit" in the pop-up window.
Save the new presentation in the same folder as the original, but assign it a different name.
Return to the original presentation, and then select the slide that precedes the slide you want to show in portrait orientation.
Select an object or text on the slide that you will click to link to the other presentation.
Select the "Insert" tab, and then click the "Action" icon in the Links group on the ribbon. Select "Hyperlink To" in the pop-up box, and then select "Other PowerPoint Presentation" from the options. Select the file name of second presentation that you saved earlier, and then click "OK."
Select the title of the slide that you changed to portrait orientation, and then click "OK" twice. PowerPoint links the selected object to the slide in the second presentation. When you click the link in the first presentation, the slide from the second presentation will open in a process that is virtually invisible to the viewer.
Create a link back to the original presentation by repeating these steps.
You can delete the extra slides from the first presentation, once you're sure you no longer need, them.
The information in the article applies to Microsoft PowerPoint 2013. If you use PowerPoint 2010 or 2007, you can change your presentation's orientation by selecting "Slide Orientation" from the Design ribbon, and then clicking "Portrait." In PowerPoint 2003, you can change the orientation from the Page Setup dialog box, which you can access from the File menu.