You may be "infected." Here's my suggested procedure for tracking down and cleaning up bad add-ons and other hijackers. I know it seems long, but it's really not that bad.

(1) Open the Windows Control Panel, Uninstall a Program.

After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. Be suspicious of everything you do not recognize/remember, as malware often uses important or innocent sounding names to discourage you from removing it. Sounds as though you need to look back quite a ways if you've had this problem for three months.

Take out as much trash as possible here. If you're not sure, feel free to post program names or a screenshot of the list.

(2) Open Firefox's Add-ons page using either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons
• in the Windows "Run" dialog, type or paste
  firefox.exe "about:addons"

In the left column, click Extensions. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions. All extensions are optional; the troublemaker might not be obvious from its name. But anything with the word "search" in the name would be a prime suspect.

Often a link will appear above at least one disabled extension to restart Firefox to make the change effective. You can complete your work on the tab and click one of the links as the last step.

Any improvement?

(3) You can search for remaining issues with the scanning/cleaning tools listed in the previously mentioned support article: Troubleshoot Firefox issues caused by malware. These on-demand scanners are free and take considerable time to run. If they finish quickly and especially if they require payment, you may have a serious infection. I suggest the specialized forums listed in the article in that case.

Hopefully that will flush anything on your system and in your Firefox that could be a problem.

Then, if necessary, you should be able to update these settings and have Firefox honor your changes:

• How to set the home page
• Change your default search settings in Firefox

Thanks so much for taking the time to reach out with a solution. I tried what you said. FF still doesn't go automatically to my selected home page, but it doesn't slam me over to Yahoo, when I do a search. Disabled the two extensions I found, and that was about it.

I am chagrined, though. I downloaded Malwarebytes and it flagged my Advanced System Care, something I've used for, what, 10 years, maybe? And on my older computers, it got me out of some jams more than once. I've heard rumors that it's some kind of Chinese trap, but since it did work for me I ignored them. I have Norton for many years, too, and it never once flagged ASC, so I'm really confused!

Anyway, thanks again for your help. I really appreciate it!

So what happens when you do this to set your homepage ? https://support.mozilla.org/en-US/kb/how-to-set-the-home-page

If still not able to set the home page it is possible there are left overs of what ever you had. Try below and you can read what Farbar puts out and might help you finsish the job or just post and wait for help. They are good at what they do. https://forums.malwarebytes.com/topic/9573-im-infected-what-do-i-do-now/

As for Malwarebytes and AdwCleaner (bought by them) they both flag that sorta program because there is screens and buttons that want you to install other stuff. So they are calling it bad. If a novice or not looking you could install all their other stuff which I have seen many, many times. But ya, is a false/positive.

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