While we're scoping the main feed to allow sorting by most recent messages (comments), I have a workaround for you. I know, it's not ideal to have to go to a different page, but as soon as we can get things sorting on the main page I'll let you know.
In the meantime, if you want to know which topics have new comments, you can see all the recent activity here: https://community.jumpcloud.com/t5/forums/recentpostspage/post-type/message
You can bookmark it if you'd like, but make sure you check back on the home page every once in a while, too. 🙂
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