I have a MacBook Pro and Firefox is my go to browser, having used it since I got my very first Mac 15 years ago or so. But it seems to have caught a virus/malware/adware, which I have been trying to fix, and now it's worse than ever.
I will try to remember everything that has happened and everything that I have done.
For probably months the home page has been something unfamiliar instead of what I wanted it to be, but I ignored it and just moved on to the sites I wanted to go to. No biggie.
Recently, I started getting pop-up windows telling me that I needed to update Java and Adobe Flash. I think I updated Java and had no other issues with that (maybe it was legitimate?), but Adobe Flash seemed to update, but I kept getting the messages.
Then the home page started opening with a congratulatory message, and I was supposed to click on it to go on. Sometimes I got a warning message that started beeping loudly! That's when I started thinking I needed to fix this. Through googling I learned that the pop-up messages were fake and also part of this issue.
I tried all the advice that I came across, unless it seemed too involved and techy. (I am not very techy.) Among the advice was clearing all history and restarting, and deleting Firefox and reinstalling. I also downloaded two virus scanners, AdwareMedic and Avast. AdwareMedic didn't find anything, but Avast found some viruses that I deleted, then restarted the computer. At that point the address bar said search.ividi.org, but the page was blank and said Page Not Found. Every new tab also said search.ividi.org.
So I tried refreshing Firefox. That's when the newest problem came up. Every single page I try to load gives me the message "This Connection is Untrusted". The error code is this: (Error code: sec_error_unknown_issuer). I have googled this too and tried everything I can find, except change settings in about:config because I am scared to. My date and time is correct, refreshing seems useless since it came to be right after refreshing.
I don't know what to do now, I only seem to be making it worse, and I don't want to give up on Firefox. I use Chrome too, but I like to use both. I don't know who to ask, hoping for answers here.
Thank you so much in advance for any help!