ฟอรั่มสนับสนุนของ Firefox

Almost daily on Firefox, I get pop-ups like the one shown in the attached image. I have, a few times, bought items on MrTortilla's website and that's fine. What I don't want it pop-ups from them daily when I'm not even on their site. Where do I go in Firefox to say, "I'm not open to pop-ups from this site"? Somehow it must be listed as okay. Please don't tell me to delete all cookies because I like the prefills from most of them. If there's a specific cookie I need to delete, please explain how to get to that. Hopefully, it's just a setting somewhere of sites that are allowed to send pop-ups and I can be guided there to remove mrtortilla.com from that list. Thanks!

For months, now, whenever I try to post a comment on a Yahoo! News article, it reads: "Your comment has failed to published." This only happens in Firefox. My "Privacy & Security" settings are set to "Standard," my "History" set to "use custom settings for history" with settings "Remember browsing and download history" and "Clear history when Firefox closes." so cookies and cache get cleared then.

Sometimes this works when starting a new session. But I shouldn't have to start another session and lose all of my logins just to post a comment on a Yahoo News article.

Anyone else having this problem? Is there an easy and permanent fix? What are you settings set at?