Another newbie question. when you get a reply on a thread, the "COMMUNITY" menu gets a violet dot, does that mean you have unread replies? How do you clear that? I clicked on each thread, and it's still marked with violet dot?

Well known bug existing for a very long time. The purple dot does not go away after you view the thread where the reply was. One way to remove it is to click clear notifications, which can only be done when you have notifications (and yes, this also means that clearing notifications will also clear the purple dot even if you do have unread replies). Otherwise, there are some commands to run to clear it manually. There's a "main" thread for this.

Besides what Cavalry replied, mind it'll be much harder to find replies to your comments after you clear your notifications. So, before you do that, I'd suggest checking that by dragging your mouse over the community tab and clicking in the "forum replies" option in the drop-down menu that appears (or access its direct link).