Final answer:
To enable unknown sources on an Amazon Firestick or Fire TV, go to Settings > Device or My Fire TV > Developer Options and turn on ADB debugging and Apps from Unknown Sources.
Step-by-step explanation:
To enable unknown sources on your Amazon Firestick or Fire TV, you need to adjust the device’s settings to allow the installation of apps from sources other than the Amazon Appstore. Please note that enabling this feature may make your device more vulnerable to security risks. Here's what you need to do:
Go to the home screen of your Firestick or Fire TV.
Select “Settings” from the top menu.
Scroll right and choose “Device” or “My Fire TV,” depending on your interface.
Scroll down to “Developer Options.”
Turn on “ADB debugging” and “Apps from Unknown Sources.” You might receive a warning message, but if you wish to proceed, select “Turn On.”
Once this setting is enabled, you can install apps from sources other than the Amazon Appstore. Remember to only download applications from trusted and secure sources to minimize security risks.