How do I force an app to landscape?
Setting the app up
When on the main screen, under the orientation section, you will see a number of options like 'Auto-rotate OFF', 'Auto-rotate ON', 'Forced Portrait' and 'Forced Landscape'. As the names suggest, you can use these buttons as one-tap shortcuts to toggle the orientation of your device.
Why do some apps only work in portrait on IPAD?
Its because the developer has blocked the orientation to portrait/landscape only.