<p>Regular users cannot convert <em>questions</em> (whole threads in practice) to community wiki.  That was once possible, but hasn't been for several years.  You can convert your own answer to CW, but that won't make the question CW or the other answers.  If you believe a thread should be CW, you have to flag the question and ask the moderators to do it.  Just click on the light gray "flag" at the bottom left of the question body, and comment that the Q should be CW and why you think so.  </p>
