HI, This could be an issue caused by AdAware or Web Companion from Lavasoft. If you have them installed uninstall them. If you have any other programs you do not know or toolbars uninstall them.

You can look for a file named dsengine.js in these locations. You should only find channel-prefs.js in the "defaults\pref" location. Any file found here apart from channel-prefs.js is suspicious. You can check the content of the file in a text editor (use open with and do not double-click the file).

C:\Program Files\Mozilla Firefox\defaults\pref\ C:\Program Files (x86)\Mozilla Firefox\defaults\pref\

You can look for a file named dsengine.cfg in the main Firefox program folder.

C:\Program Files\Mozilla Firefox\ C:\Program Files (x86)\Mozilla Firefox\

Delete the dsengine.js and dsengine.cfg files when present.

Please use more than 1 scanner as each uses diff tech :

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

Save your Report and google each before deleting anything as do not want to delete something you need, If need help :

• https://forums.malwarebytes.com/topic/9573-im-infected-what-do-i-do-now/

Post in only 1 forum, then wait.

Please let us know if this solved your issue or if need further assistance.

Hi chris-1685, my first question is where you are searching from. Firefox can control the search engine when you search within Firefox, but when you search using the Windows system search bar (on the main task bar or on the Start menu), then Windows (or Cortana) settings take precedence over your browser settings.

Back in 2015, Firefox added the ability to detect searches sent from the system and switch the query from Bing to another site if the user turned that on. However, Microsoft made frequent changes to the search URL which could bypass that feature, so that seems to be defunct now. You could try an add-on to redirect Bing queries to another site now.

(If you have an add-on that is causing Firefox to use Bing now, you'll need to remove that first.)