Steps to reset Firefox to default settings:

• Launch Firefox.
• In the upper right corner of the Firefox window, click the hamburger menu. This brings up a dropdown menu with the majority of the browser options you may change without resorting to authorized browser hacks.
• Near the bottom of the screen, click Help.
• From the Help menu, select Troubleshooting Information.
• On the Troubleshooting Information screen, click Refresh Firefox in the top right corner.
• Mozilla will then notify you that you're about to uninstall all of your browser add-ons and revert to the default settings. To put it another way, you're about to undo everything you've ever done in the browser. To continue, click Refresh Firefox.
• You'll see a success screen after Mozilla refreshes the browser
• . To continue using the browser in its newer, cleaner version, click Let's Go.

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