1. Open Firefox
The Firefox icon shows a fox coiling around the world. Then, on Windows, click Ctrl+T or Command+T on Mac OS to launch a new browser window.
2. Visit the Advanced Configuration url
In the address bar, type about: config and press Enter or Return. A list of browser settings will open. To quickly go to this list, create a bookmark on it. To do this, press Ctrl+D (Windows) or Command+D (Mac OS).
3. Accept the warning about changing advanced settings
In the window that opens, click “I promise I’ll be careful”. Keep in mind that the settings that open are intended for advanced users only. Do not change the settings if you do not know what it will lead to (this may cause the browser to work incorrectly).