I did a search and found a listing saying that securedsearch.lavasoft " Securedsearch.lavasoft.com is the PUP that uses misleading techniques to prevent removal. "

As a test, disable this add-on.

Do a clean reinstall of the current Firefox release and delete the Firefox program folder before installing a fresh copy of the current Firefox release.

• download the Firefox installer and save the file to the desktop
  *https://www.mozilla.org/en-US/firefox/all/

If possible uninstall your current Firefox version to cleanup the Windows Registry and settings in security software.

• do NOT remove "personal data" when you uninstall the current Firefox version, because this will remove all profile folders and you lose personal data like bookmarks and passwords including data in profiles created by other Firefox versions

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• (64-bit Firefox) "C:\Program Files\Mozilla Firefox\"
• (32-bit Firefox) "C:\Program Files (x86)\Mozilla Firefox\"

• it is important to delete the Firefox program folder to remove all the files and make sure there are no problems with files that were leftover after uninstalling
• http://kb.mozillazine.org/Uninstalling_Firefox

Your personal data like bookmarks is stored in the Firefox profile folder, so you won't lose personal data when you reinstall or update Firefox, but make sure NOT to remove personal data when you uninstall Firefox as that will remove all Firefox profile folders and you lose your personal data.

• https://support.mozilla.org/en-US/kb/Profiles
• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Reinstall Firefox

• https://support.mozilla.org/en-US/kb/troubleshoot-and-diagnose-firefox-problems

Securedsearch.lavasoft.com is a browser hijacker that (among other things) changes your home page ....

See : https://www.bugsfighter.com/remove-adaware-secure-search/

And also : http://www.pccaretips.com/blog/how-to-get-rid-of-securedsearch-lavasoft-com-redirect-virus.html

It might be a good idea to run all malware scans that are listed in this article : https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware