How to Change Advanced Settings in Mozilla Firefox


I consider Mozilla Firefox to be the most versatile browser. It has tons of add-ons available. It is very fast and can be very secure if set up correctly. And users also have the possibility to change and fine-tune every possible setting in it.

The complete list of settings can be found by typing and entering about:config into the address bar of Mozilla Firefox.



At that point a warning message appears urging you to be careful while tinkering with these settings. But after you promise to be careful, you can go on.

At the top of the window you can search for any term you like. The results will show up automatically, even as you write.

There are a lot of advanced settings listed, so I will focus only on the ones that I changed in my computer.

Downloads Folder

To set your preferred downloads folder, search for:

This variable has a string value. By double-clicking on the line a pop-up window opens where you can enter the location of your downloads folder.

Opening Links in New Windows/Tabs

To select how you want Firefox to handle the target=”_blank” parameter in links, search for:

This variable has an integer value, meaning that it can be any whole number. To make Firefox open links in a new window set the value to 2. To open these links in a new tab, set it to 3. Any other whole number will open these links in the current tab. The default setting is 3.

Search Engines Opening Search Results

To select how you would like Firefox’s search engines to open links for your search keywords, search for:

This is a boolean variable, meaning that it has only two possible options — true or false. The default setting is false.

However, I found that sometimes I have a tab open and I remember to search for something completely unrelated in the Wikipedia search engine. (The search engines in Firefox are located right next to the address bar.) It is much better to have the results of that search open in a new tab rather than messing up the project I work on in the same tab.


In the case of boolean settings, it is enough to double-click on the line and the setting will automatically change.

Close Buttons on Tabs

To select whether you would like to have close buttons on your tabs, search for:

This is an integer variable. Its possible values are: 0 (there’s a close button on the active tab only), 1 (every tab has a close button), 2 (there are no close buttons on any tabs), or 3 (there is one close button only at the end of the tab bar). The default value is 1.

Unfortunately, this popular setting has been retired as of Mozilla Firefox version 31. But not to worry, there’s an add-on available that brings back at least partially its functionality.

Closing Last Tab Exits Firefox

To set whether closing the last open tab will also close Firefox as a whole, search for:

This is a boolean variable. The default setting is true. But experience taught me to set it to false — I closed the last tab and then restarted Firefox too many times…

Mouse Middle-Click Opens Links in New Tab or Window

To select whether middle-clicking with your mouse on links makes them to open in a new tab or a new window, search for:

This is again a boolean variable and its default setting is true. Setting the value to false will result in opening such links in a new window instead of a new tab.

Geographical Location

To choose whether your physical location should be revealed to web services requesting this information, search for:

Again, this is a boolean variable. The default is set to true. However, I am a private person therefore I changed this to false.

Zooming the Layout In or Out

To change how Firefox displays the layouts of visited websites, search for:

This is a string variable and it’s set to 1 by default. You can change the value to 1.15, for example, to zoom in by 15% compared to the default setting. Similarly, you can set the value to 0.85 to zoom out by 15% compared to the default setting.


To set how many pixels should Firefox scroll at a time, search for:

This is an integer variable. The default value is set to 20. The higher you set this number, the more pixels will be scrolled in one increment. You have to try this out to find out your personal preference.

As I said Mozilla Firefox has a lot to offer settings-wise. This is just a taste of the many options available. I tried to select settings that I have experience with and that I also find generally useful.

Final Thoughts

I hope that you will find them useful, too. In any case, let me know in the comments below.

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