While the Yahoo search engine can be removed, it would be restored with every Firefox update. The default search engines, those that come with Firefox, are "protected"; they are packaged in the omni.ja file which is replaced with the new version of the omni.ja that comes with every new version & dot-number sub-version (a "chemspill" release version between the scheduled releases).

See this to learn how to change your default search engine in Firefox. https://support.mozilla.org/en-US/kb/change-your-default-search-settings-firefox

If that isn't working for you please explain in greater detail.

f0xfield said

Just posted about not being able to remove Yahoo as search engine, even when following directions given in the firefox web page. However, i have the wrong email address - had fieldffox instead of fieldfox! So, if you answered why the firefox web page does not work - or better still how to remove yahoo and get the google search engine working in firefox, please sent it to me.

We don't send answers via email - we give them here, on the support forum.

If you have followed all the steps to remove Yahoo as a search engine, then I get the feeling that you're dealing with search.yahoo.com, which is a browser hijacker. If that's the case :

Go to the 3-bar menu (or   'Tools') => Addons => Extensions and look for any unfamiliar or suspicious looking extensions, like e.g. :

SafeSearch Incognito SearchAssist Incognito Search for Fire Fox 1.6 SafeSearch ch SafeSearch net File Convertor and Search Addon

When you find any : remove them.

Do the same in Windows' Control Panel => Programs.

However :   most malware will be 'hiding' somewhere , so let's run malware scans :

Further information can be found in this article :
https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no

Run most or all of the listed malware scanners.
They all work differently   -   what one program doesn't pick up, the other might.

Also see : https://malwaretips.com/blogs/yahoo-toolbar-removal/

Please be assured that Firefox is designed to let you select your preferred default search engine -- this is separate than the list of available "one-off" search engines -- and have it stick permanently. If yours does not stick, it is nearly always a problem caused by an extension, and that extension may be something you installed without realizing its nefarious behavior or that rode along with something else you installed. Please see the reply from Happy112 for next steps to track it down and eliminate it.

And finally, if this is your earlier question, please add a reply asking for it to be locked so people do not reply to a question you're not interested in:

https://support.mozilla.org/questions/1180442

I must have the malware as I am able to access the "page" listing the selected search engine and the block listing several such engines. I change the selected search engine from Yahoo to Google, then remove all other search engines listed (except Google) and then when I search, Yahoo pops up!

Have been reluctant to try malware remover as I fear I might just be adding more problems.

Thanks for the responses and tolerating my ignorance!

f0xfield said

Have been reluctant to try malware remover as I fear I might just be adding more problems.

Quite understandable, but absolutely no need to be afraid - if you want to get rid of this malware (which of course you do) you wil have to run all of those malware scans (just a one-off).

Thanks for the responses and tolerating my ignorance!

I haven't noticed any ignorance ........