I too would like this feature. In many of the posts I've seen, it says you can change your thumbnail picture by right clicking on the picture but I do not see an option when I right click to "set as thumbnail image". Am I missing something? I have a template I use daily and the picture at the top of the template gets set to my thumbnail everyday... even if I delete that picture it still stays as the thumbnail. I would like one of the new pictures I add that day to become my thumbnail picture instead.