Firefox has always maintained a reputation for being an enormously customizable program right from its debut, both through its add-on architecture and its internal settings. As many of Firefox's settings aren't exposed through the Tools > Options menu; the only way to change them is to edit them manually. Some of the most useful Firefox settings that you can change on your own and that aren't normally available through the program's graphical interface.
Firefox does not manage its internal settings is the Windows Registry. Each setting, or preference, is given a name and stored as a string (text), integer (number) or Boolean (true/false) value. Firefox stores its settings in a file called prefs.js found at
You can edit prefs.js directly, but it's often easier to change the settings through the browser window.
Type about:config in the address bar and press Enter, and you'll see all the settings currently enumerated in prefs.js, listed in alphabetical order. To narrow down the hundreds of configuration preferences to just the few you need, type a search term into the Filter: bar.
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