Hi,

Even though Yahoo is a legitimate search engine - you may be dealing with Search.yahoo.com redirect virus.

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

When you find any : remove them.

Do the same in your system's Control Panel.

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.

Especially for Mac : https://www.malwarebytes.com/mac/

Also see : https://www.pcrisk.com/removal-guides/8835-search-yahoo-com-redirect (scroll down some to Mac OS)

Also look for SafeSearch, SearchAssist Incognito, FileConverter Addon, SearchLock, DiscreteSearch, WebSearch, Findwide Search Engine

Now do the same in the computer’s Programs Folder.

FredMcD said

Also look for SafeSearch, SearchAssist Incognito, FileConverter Addon, SearchLock, DiscreteSearch, WebSearch, Findwide Search Engine Now do the same in the computer’s Programs Folder.

Yes, like I said in my post :

look for any unfamiliar or suspicious looking extensions.

Hey, thanks a million for the help! I tried the automated techniques but they didn't work. The manual steps outlined on pcrisk.com did the trick. I think we're clean now.

Take care....