LOOKS LIKE I WAS RIGHT - MOZILLA/FIREFOX DOES NOT CARE ABOUT IT'S CUSTOMERS

I'm sure that it's impossible to block ALL adverts, in the same way that it's impossible to know exactly which days it will rain in your area. Everybody tries their best but people and tools are fallible. To block the vast majority of adverts, though, do install the uBlock Origin addon:

https://addons.mozilla.org/en-US/firefox/addon/ublock-origin/

While you can tweak the configuration for even better performance (the user interface isn't the simplest), it does wonders just out-of-the-box.

As an aside, bear in mind that (to the best of my knowledge) this forum is staffed only by volunteers. A question posted in the morning is more likely to get replies in the evenings or overnight, when people are home from work. I am here myself because I offered to help a user with a website login problem, and while checking the status of his post, looked to see if I could address a new issue or two as well.

UBlock Origin is widely recommended. You may also consider using a hosts file.