Ok I just got a new little lenovo notebook which had only Windows Edge for internet browser so I installed IE and Firefox because that's what is on my old laptop. anyway I guess I already had Firefox opened under the IE browser so when I closed IE the Firefox browser was left and there was a couple of boxes over the page telling me I needed to update Firefox and there was something about a scan but when I looked at the URL it did not have Mozilla or Firefox anywhere in the url. Well I immediately opened task manager and closed it out that way. I then downloaded CCleaner and did the analyze and clean. After that i reopened FF and now I am here. so far nothing has popped up telling me to update. So my question is does FF request updates in this manner and what would the url be? I have Defender which is just like Microsoft Security Essentials for windows 7. Apparently Defender for older OS windows 7 only protected against spyware. But Defender for Windows 8-10 is full protection. I did not have any alerts regarding this security update for FF with my Defender protection so I'm not sure if that update was legit. I just want to know how to tell if updates are legit and if not, is using task manager to close applications the proper way to prevent further attempts of infecting my pc with viruses ,etc.?

an ounce of prevention is worth a pound of cure, yes?