Debug settings menu instructions
Instructions to enable the “secret settings” in the Settings menu for Firefox Nightly. This lets you access “Secret Settings” and “Secret Debug Info” in the Settings menu.
Tap on three-dot menu in the toolbar
Tap on Settings
Scroll down and select “About Firefox Nightly”
Tap the Firefox logo until you see the “Debug menu: (#) click(s) left to enable” helper message
Once the Debug menu has been enabled, go back to Settings and you will see “Secret Settings” and “Secret Debug Info” menu items