iMac running MacOS Mojave version 10.14.5, Firefox 67.0 After updating Firefox found You Tube would not load. Entering a URL, the You Tube logo appears upper left but no You Tube search window. To the right of where it is absent are four light grey circles. Lower down are some more circles and longish rectangles. I have no Firewall, which was one suggestion I came across. I had the problem after the Firefox update and updated Mojave in the hope that this would resolve the issue. Would appreciate any suggestions be presented in clear and simple terms as I don't know much tech jargon.