Extremely strange behavior - wicked virus?

Hi my pc is doing all sorts of strange things. I constantly feel as if I'm chasing my tail when trying to accomplish anything...I know technology doesn't always do what we want but this seems to be something else. I have this idea that there are AI virus nowadays (and that's what I have) that screw with your computer as you click through things so that there is no boundaries to how it can cause frustration and pain. These are just a few of the things I'm experiencing...taken one at a time it's not the end of the world of course by patience is running thin.

1. Firefox - customization doesn't work properly...I try to change font size and it just doesn't work. It has a great feature that other browsers don't to override the site's native font but it's all screwed up. 
2. Firefox shows a whole ton of things in the bottom left status bar once in a while and moves to a crawl.
3. On Substack, I click a comment icon which shows 7 commments, and only one shows up with the text box for me to comment...if I go and jump through hoops by clicking here and then there and scrolling down to the bottom of a complete post, then I can view all the comments...
4. Also on substack, after scrolling for a while and finding something of interest...I'll click to pull 'it' up and then hit the browser 'back' button. It doesn't return me to where I was on the previous screen... EVERY browser does this...so I can't pick up where I left off. I just sent an email to them to see if this is normal behavior.
5. I ran a virus scan with defender and after it took hours...in the recent scans it shows scan took merely minutes to complete...which it didn't
6. My pointer flickers the time sand capsule icon quite a bit for no reason...like 5 times at a clip
7. I have to click buttons 2 and 3 times to function.
8. I get like three dos-like type windows that kind of show up randomly for .5 seconds in a cascading type view...very hard to explain this one.
9. Of course defender and malwarebytes aren't finding anything.

Best of all, I just did a complete system reset to fix the issues I was having.

Much appreciated if someone can help me out.

-Travis