Need computer help

[GoatDriver]

In Firefox follow the screenshots below

 

[flyerdan]

It really won't do any good switching back until you find out what's causing the takeover, I'd run Spybot and see if it can root out whatever malware is responsible, then put the search engine right.

 

[Toyboy]

If you are using Firefox click on Tools, Options, Search and delete Yahoo from the search engine list. If Yahoo is not listed then you have a virus running that is redirecting all of your searches to something that appears to be Yahoo but probably isn't.
If you have one of the browser redirect viruses here is a fairly good write-up on getting rid of it.
https://malwaretips.com/blogs/remove-browser-redirect-virus/

Thanks for the links I think I killed it. I tried TDSSKiller first and it could not find anything. Next I went to RKill with the same results. Finally I went to Hitman Pro and that is the one that found and deleted it. Don't ask what it was because I just hit the kill button and all seems fine.
Thanks to all for your many suggestions and help figuring this out.
Terry

 

[kcflhrc]

I have used Hitman Pro in the past with success, glad you figured it out.

 

[Toyboy]

I have used Hitman Pro in the past with success, glad you figured it out.

LOL...I didn't figure it out, you guys did.