Checkout this video:
Open the Firefox browser and type “about:config” in the URL bar
This will open the Firefox configuration page.You may see a warning message.Click “I’ll be careful, I promise!” to continue to the about:config page.
1. In the URL bar, type about:config and press Enter.
2. Click I’ll be careful, I promise! when prompted.
Close the about:config tab
About:config is a page that lets you modify the Firefox configuration. It’s possible to make some serious changes to Firefox by changing the values on about:config, so be careful.
1. Type about:config in the Firefox address bar and press Enter.
2. A warning message will appear. Click I accept the risk!.
4. Double-click on the preference to change its value from false to true.
5. Close the about:config tab when you’re done.
1. In the address bar, type about:config and press Enter.