If you want to disable automatic spelling correction on Amazon Kindle Fire then guide below will help you to do that, as the feature is enabled by default on the device.
Disable Automatic Spelling Correction on Kindle Fire
On your Kindle Fire’s home screen, tap on “Settings” icon, which resides in right upper corner of screen
Tap on “More” > “Kindle Keyboard”
Toggle the slider to OFF besides “Quick fixes” and that’s it
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