If you click on that symbol seen in the screen-shot marked by that arrow this will mark a question as favorite, which you can then see in your profile under favorites, and it even shows you by a blue number on the favorites tab that there was activity, so you only need to click on this tab when there has have happened to be activity on that question.

[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/aAJL4.png