Community Gallery: Changing the order of photos?

I want to update my album in the community gallery.  I'd like to move some pictures around and change the thumbnail highlight.  But when I click on "change the order," I'm told that there's an automatic order command on my album that I have to remove.  Trouble is, there's no way to remove it.  What do I do?

Also, when I try to make a new photo my highlight, it refuses to happen.  Any advice?  Thanks!