Sometimes the screen on the Amazon Kindle Fire will rotate annoyingly when you’re trying to read. Fortunately you can lock the screen in place and disable the screen rotation.
I wondered what the Locked and Unlocked icon meant when you tap the settings gear. It turns out, that is the setting that disable screen rotation.
Tap the icon to toggle the setting. When it says Unlocked, screen rotation is enabled.
When it says Locked, screen rotation is disabled.