I did some searching on how to fix this on Google and there was a suggestion to click "disable this service" at the bottom of this Webhelper page. After I click disable and save, and check by typing a partial address, the same Webhelper page shows up and when I click to disable it again, I see the setting is enabled again!!! This makes me think one thing: hijacking! I also tried clicking on the "why am I here" link at the top of the page and opting out, but that also changes nothing.
When I type another partial page to see what will happen, I get the same obnoxious "webhelper" page that I never set up as a default for "page not found", and the settings I just changed to disable the page are once again showing enabled.
I recently reset my home page again because CenturyLink webhelper had taken over that as well.
This is not happening with Chrome, which I also use and prefer at this point because of this problem with Firefox.