7) They are sorted by 

![enter image description here][1]

<strike>
and even more funny: I think the sorting stays till **YOU** change it.
Check [this](https://math.stackexchange.com/q/284590/19341) where I sorted
it by "oldest" and change it. The next viewer should see your sorting option
(maybe you post it as a comment to keep some track).

It least this is what I found by using my PC and tablet in parallel...
</strike>

  [1]: http://i.stack.imgur.com/y1njm.jpg