Hello,

This may be one of two things, either a study by Mozilla or a hijacker.

As a part of optimizing the Firefox experience, Firefox regularly runs studies. Firefox is currently running a study that may cause some users to notice that their default search engine has changed. To revert to your search engine of choice, please follow the steps we have at Manage Firefox search settings.

If you have a program that has taken over your search engine, home page, and/or the default new tab page, you can remedy this as following:

1. Click the menu button The image "fx57menu" does not exist. and choose Add-ons.
2. In the Add-ons Manager tab, select the Extensions panel.
3. Select the toolbar you wish to remove.
4. Click the Remove button.
5. Click "Restart now" if it pops up. Your tabs will be saved and restored after the restart.

For further information, please read Remove a toolbar that has taken over your Firefox search or home page.

Did this fix the problem? Please let us know!

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or userChrome.css is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

You can do a malware scan just to be sure.

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware