Pramod,
You can change the report page setup in 2 ways.
1. Go to Design Mode -> page setup -> page(see the below screenshot for the same)
Image may be NSFW.
Clik here to view.
2. Go to design mode -> right on the report - > format report -> layout ->page layout -> page size
Image may be NSFW.
Clik here to view.
Regards
Sri Harsha