There may be other programs reinserting them into Firefox. Unfortunately, there are some dirty tricks that make that possible.

Since you are already familiar with the Add-ons page, I suggest these additional actions:

(1) Open the Windows Control Panel, Uninstall a Program. After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help surface undisclosed bundle items that snuck in with some software you agreed to install. Be suspicious of everything you do not recognize/remember, as malware often uses important or innocent sounding names to discourage you from removing it. Take out as much trash as possible here.

(2) Scan for remaining troublesome programs with the scanning/cleaning tools listed in our support article: Troubleshoot Firefox issues caused by malware. These on-demand scanners are free and take considerable time to run. If they finish quickly and especially if they require payment, you may have a serious infection. I suggest the specialized forums listed in the article in that case.

(3) Clear potentially malicious files from Firefox's program folder using:

Clean Reinstall

We use this name, but it's not about removing your settings, it's about making sure the program files are clean (no inconsistent, corrupted, or alien code files). As described below, this process does not disturb your existing settings. Do NOT uninstall Firefox, that's not needed.

(A) Download a fresh installer for Firefox 39.0 from https://www.mozilla.org/firefox/all/ to a convenient location. (Scroll down to your preferred language.)

(B) Exit out of Firefox (if applicable).

(C) Rename the program folder, either:

(64-bit Windows folder names)

C:\Program Files (x86)\Mozilla Firefox

to

C:\Program Files (x86)\OldFirefox

(32-bit Windows folder names)

C:\Program Files\Mozilla Firefox

to

C:\Program Files\OldFirefox

(D) Run the installer you downloaded in #1. It should automatically connect to your existing settings.

Any improvement after this reinstall?

Note: Some plugins may exist only in that OldFirefox folder. If something essential is missing, look in these folders:

• \OldFirefox\Plugins
• \OldFirefox\browser\plugins

(4) Remove any user.js file in your profile folder. You can access that folder while Firefox is closed by pasting the following into the Start menu search box and pressing Enter:

%APPDATA%\Mozilla\Firefox\Profiles

Here you should find one or more semi-randomly-named folders. Click into each and check for a file named user.js and unless you created it yourself, delete it.

Note: by default, Windows hides the .js file extension. To work with files accurately, I suggest setting Windows to show all file extensions. This article has the steps: http://windows.microsoft.com/en-us/windows/show-hide-file-name-extensions

Are things better?

"why add-ons are installing without my approval? "

That is a sign of malware getting installed without the users knowledge. A user installs a seemingly innocuous "free" program or utility without the user being offered an "opt - out" option for "extras" the user didn't want, and the user then finds out later that it contained adware as an unexpected "bonus". As far as removing the "add-ons" goes, until the original "source" is removed that adware or the add-ons will continue to reinstall itself upon Windows boot-up or restart. The "carrier" of that plague needs to be dealt with, too.

That said, there is a "fix"coming in Firefox 40 thru Firefox 42 that happens in 3 "stages" by way of the "signing" of all extensions.

• Firefox 40: Firefox warns about signatures but doesn't enforce them.
• Firefox 41: Firefox will have a preference that allows signature enforcement to be disabled by the user.
• Firefox 42: Release and Beta versions of Firefox will not allow unsigned extensions to be installed, with no override.

https://wiki.mozilla.org/Addons/Extension_Signing https://blog.mozilla.org/addons/2015/02/10/extension-signing-safer-experience/ https://blog.mozilla.org/addons/2015/04/15/the-case-for-extension-signing/