I'm sure you guys also experienced this problem. When you want to make a single landscape page, all pages follow the same. Here is how to make only single page in landscape layout.
1. Go to the last page you want to keep vertical (Portrait) then select Page Layout » Breaks » Next Page
2. Now click anywhere in the page where you want to have the horizontal page (Landscape) and go to Page Layout » Orientation and select Landscape
3. Do the same steps for the following page, the one after the landscaped one, but this time choose Portrait. Only do this if you want to restore the Portrait orientation back to normal.
Now, you're know it. :)