Sounds like malware or something similar.

Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller (for more info, see this alternate TDSSKiller download page)
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• Hitman Pro
• ESET Online Scanner

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

I'm sorry, I totally forgot to mention that I did run a malware/spyware removal tool as well last week & that did not fix the issue. Is there any other way to resolve this, or maybe a way to figure out exactly what's causing the issue so that I could remove it manually? I am SO at the end of my rope, ya know?

I will go ahead & try a different malware removal tool just to see, but if that doesn't get rid of it, do you have any other suggestions?

Thank you VERY much!

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.

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.

Thank you Fred McD! So the only extension I have installed is Grammarly. I also don't have any of those items installed on my computer, I have checked over my installed programs AND SERVICES with a fine tooth comb & cannot find anything suspicious. I don't know where it's hiding. I know it's there somewhere, otherwise this wouldn't be happening. I just ran Malwarebytes & it found 10 items & they're in quaranteen & now when I search in the address bar, it uses Google, like I have it set to do in the options.

Thank you both so very much!

Well done.

I have the same problem. There are no apparent troublesome files displayed in control panel; there is no Bing search engine listed in search engines, only google; there are only 3 extensions - colorzilla, a youtube downloader I've had on there for ages and amazon assistant, which seems to be friendly (??); I've run Hitman pro, which only found doubleclick.net - a cookie that keeps coming back; I've run adw which found nothing, and Malwarebytes, which found nothing, also Roguekiller likewise. When I open manage data, however many times I remove the 3 or 4 cookies that relate to bing, they come back immediately (sometimes one at a time, but if I leave it a while, there are 3 or 4 of them. I've searched the Mozilla program files, but don't really know what I'm looking for. Several months ago, when the same thing happened, I accidentally removed my whole profile, so firefox 'forgot who I was'. It worked though - no more Bing for a long time; a few weeks ago I managed to remove a similar chromium hijacker, but this bing is persistent - and occasionally yahoo joins it.

Any suggestions before I go through a factory reset, which would be a nightmare of reloading programs, which I really don't have time for?

I should add that if this beasty is embedded in my firefox profile, might it just come back anyway?

silvamayflower Please go to the top of any support.mozilla.org web page and use the Get Community Support link: https://support.mozilla.org/en-US/questions/new

Select the product for what the problem is (Firefox or whatever). Now select the category for the problem. At the bottom is Other.

Describe the problem in brief (one line). Then press <enter>. The website will display any prior posts that might help you. If nothing on the list can help, at the bottom press the button; None Of These Solve My Problem.

Now enter all the relative information on the problem. At the bottom of this, you can Add Images.

Under this is Troubleshooting Information. Please press the Share Data button. This will let us look at your system details. No Personal Information Is Collected.

...a youtube downloader I've had on there for ages...

If I were placing a bet, it would be that one.