The "glasses" appear for threads that you have posted in as long as in "Preferences" the "Watch threads that you post in" box is checked. The default is, I believe, that this box is checked.
If you've posted in a thread and don't want to watch it you can open that thread and click on the "Unwatch Thread" link in the upper right hand corner of that thread.
Similarly, if you want to watch a thread but don't want to post in it, you can go into that thread and click on "Watch Thread" and you'll get notifications when someone posts to that thread.
On threads that you originate "bump" will appear below the "glasses." If you want to move that thread back to the top of the list without posting anything new in it, then you click on "bump" and it will go back to the top of the list.