hello thekev99, you may have malicious addons present. please try these steps:

1. reset firefox (this will keep your bookmarks and passwords)
2. afterwards go to firefox > addons > extensions and in case there are still extensions listed there, disable them.
3. finally run a full scan of your system with different security tools like the free version of malwarebytes and adwcleaner to make sure that adware isn't present in other places of your system as well.

Troubleshoot Firefox issues caused by malware

Please follow the steps in this article:

Hope this helps.

I use Malwarebytes, it rocks

I used Malwarebytes and it says it did find and remove lots of issues, but it didn't remove the Offers4U. Also, I went into both Control Panel/Unistall Programs, as well as, Firefox/Add-ons/Extensions and and Offers4U is not listed.

What else can I do to remove this thing? Thank you.

I found this article, see if it help you:

I also found this where it is suggested to uninstall software you don't know and use Adwcleaner run as administrator among other tools.

Want to remove "offers4u pop up" malware from your PC, Then simply follow the tutorial mentioned in this Blog.

Offers4u Browser Hijacker is a redirecting virus that redirects all your searches to its sites to generate traffic to their sites, gathering search terms and redirect users to websites from where they’ll receive a commission or some sort of revenue. To remove such type of redirecting virus