This option is only for existing posts. We have a lot of clients with existing websites, in this case you have to edit every single post. For this reason we made the global settings.
and why the title sohouldn’t appears by default???
This told us many user, they want to have control over the headlines, that’s why we made this.
could yuou also reply to my question about categories?
Sorry, don’t saw the other question. Do you mean this page here (category page for “news” category)?