You could install the noScript firefox addon. It will stop scripts running for all websites and other ad stuff, unless you permit them to run. It can also stop pop-ups though Firefox can also do that itself.I went to "Cookies and Site Data" in Firefox Settings->Privacy & Security and typed in the website I wanted to block but it didn't work. Is there another way to block websites from popping up? Firefox is up-to-date. Using Windows 10.