This blog has mainly been used as an upstream source of information, but there's no reason why it can't work the other way as well. People should be able to pose questions here and see if the collective wisdom of the Apple community can supply the answer.
Let me get the process started. For the last several months, whenever I've started to watch a video on screen, whether I've clicked on the play (▶︎) button or relied on AutoPlay, it always begins with the sound muted, and I have to pause it while I manually unmute it. For whatever reason, my iMac never seems to remember that this is the way I prefer it, and I have to do it again the next time. This is an annoyance, and I've right-clicked all over the video controls and looked in System Preferences to see if I can figure out what's causing it and how I can specify my own preference for not always starting up with the sound muted, but no dice.
Anyone got any advice?