I think if you click on your name, your profile comes up across the bottom. I see (cause I can see everything) that you have notifications there and there are probably some settings.
New messages on a topic are at the top and you click on Subscribe..
It’s all new to all of us too. Back when I built the old site with my stone tools, I had more control but it was also a LOT LOT harder. This new format is like putting it together with Lego blocks – you don’t have the control but even I can do it…