Medium does frown on certain things and now I can’t remember for sure the exact title change specifications. But title changes were definitely mentioned because people were changing the title and basically republishing content they had already written. So you can update your articles in terms of editing but you have to be careful with title changes if the rules are still as they used to be. Like I said I’m not sure but people shouldn’t change a title without looking into the rules because it could get them into trouble. I’m guessing it might be okay to reframe a word or two but completely different titles on old content is prohibited to my knowledge.