Change the Page Set Up

Slide size and orientation can be found on the Design Ribbon, next to the Themes.

 

2. Try it: Change the Page Setup

Go to Design ->Page Setup.

Click on Page Setup

 

Try This, as well: Edit the Page Setup

Slides sized for: Custom

Width: 8 inches

Height: 10 inches

Slide Orientation: Portrait

 

Click OK. Keep going, please...

Design ->Page Setup->Page Setup

Exam 77-883: Microsoft PowerPoint 2010

2. Creating a Slide Presentation

2.2. Apply slide size and orientation settings: Setup a Custom Size