Why are so many kids apps are in landscape mode?

Landscape Mode is generally used to display more "visual" or "interactive" content. Most applications for kids are usually going to be interactive or try to present content in a visually engaging way, rather than trying to achieve high information density, and cramming the most information into the smallest space.

1. How do I force an app to portrait mode?
2. How do I force an app to rotate to landscape?
3. Do all apps work in landscape mode?

How do I force an app to portrait mode?

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.

How do I force an app to rotate to landscape?

Android Settings

In Android devices that are fairly up to date, there are a few settings you should check. Start by going to Settings => Display and locate the “Device rotation” setting. On my personal cell phone, tapping this will reveal two options: “Rotate the contents of the screen,” and “Stay in portrait view.”

Do all apps work in landscape mode?

Not all Apps are coded to operate in both Portrait and Landscape screen orientation. If the App does not support one or other screen orientation, there is nothing that you can do to work around this limitation.