What happened to the sound when watching PBS?

OK. This is embarrassing, but here it is. The whole situation got really complicated because I started having problems with Edge and Chrome as well as Firefox. I finally got a response from a tech guy at PBS, and he told me that the local station's membership listings sometime get out of sink with the PBS HQ membership listings, or whatever. He reset my listing and ... bingo ... I was able to sign back into Passport on Edge and Chrome successfully, with both video and sound. But still no sound on Firefox. So, I'm sitting there with Firefox open and the splash page for PBS Passport up and open on my screen when I notice, down in the lower right-hand corner, four little symbols. I'd never noticed them before, and they only appear on the splash page, not on the page specific to a particular program. Alright, I examine them more closely, and one of them looks like a "sound" symbol. So, I click on it and ... bam ... I've got sound again. That was the problem the whole damn time. How it got turned off or how I turned it off in the first place, I do not know. What's really frustrating is how hard it was to figure out that that was the whole problem, at all. I had looked for a sound symbol earlier, up in the menu at the top, where the controls usually are, and there was nothing. And no tech support person asked me, "Did you check the symbols in the lower right corner of the splash page?" In short, the problem got solved by accident. But I still don't understand why it was turned off only on Firefox. Sigh. But thanks for responding. I really appreciate that you did. JT