This might be affected by theme but there’s normally a Subscribe link, and if you’re already Subscribed then it changes to an Unsubscribe link. Like in the sidebar of this thread, above Favourites and below Last Activity.
Thanks a lot for your answer!
Unfortunately for me I do not have the Topic info anywhere (is that a widget? Where can I get that?)…
The only thing I have is a “Notify me of follow-up replies via email” tick box under the reply box, like the one on this page.
I do not think it is the theme because I never saw those links before and I changed theme two three times since I am using bbpress :/