Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; (<Control> [Mac=<Command>] <Shift> A)

In the Add-ons Manager, on the left, select Extensions. Remove “ Yahoo “ Anything.

Also remove SafeSearch, SearchAssist Incognito, FileConverter Addon, SearchLock, DiscreteSearch, WebSearch, Findwide Search Engine, securedsearch

Now do the same in the computer’s Programs Folder.

Windows: Start > Control Panel > Uninstall Programs. Mac: Open the Applications folder. Linux: Check your user manual.

Recently, some users have had such a bad infection that the Add-ons page wasn't accessible in normal mode. They had to restart Firefox in its Safe Mode to be able to investigate their extensions. Here's how:

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" Help button > Restart with Add-ons Disabled
• (menu bar) Help menu > Restart with Add-ons Disabled

and OK the restart.

If Firefox is not running or that method is blocked: Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.)

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Then you should have full access to the Add-ons page. Consider removing anything you aren't sure is useful and safe.