Major editing problem with Blogger, cannot save as draft or re-publish edited version

I cannot publish a post on the page I write it on, only can save it there. I can only publish it from dashboard. THEN after a post is published I cannot edit it at all: it will not save as a draft or re-publish even if I change the date or time. I can type an edited part in, but cannot get it published.
So, I have had to edit a published post, put it into a NEW post, delete the old post and publish the new post with edited content. THE PROBLEM is when people and sites have my original URL for the post, they will no longer find it. WHen I need to edit a published post, I have just been adding the edits in my own comments area. WHAT IS WRONG with Blogger and how can I fix it???