Thank you, Nicola! I had never clicked on Post Options when I was writing a post - and there are windows for the date and time of a post :-)) Quite easy to change, as Nicola said.
So now I don't need to do posts like this:
My new post is here: "Collecting Short Storeys": Molly Fox's Dolls House Collection. Because I started it 3 weeks ago, that's where it shows up in the list of blog posts!
4 hours ago