According to this web site How to Change the Author of a Post in WordPress it should be possible to change the author of a post to another (existing) account. Following this description I activated the author field in the Screen Options and should see an author box on the right besides the post.
The author box does not show up, so I cannot change the author.
I have tried to activate/deactivate other options, and it seems to me that most of them do not make an actual change. (Deactivating the post image box does, others do not.)
Open an already published post.
Open the Screen Options menu.
Activate the author box.
Author box will not show up.
It doesn’t matter whether an administrator account or an editor’s account tries to do that.
In a relatively new blog I had written a few articles with the administrator account instead of my editor’s account, and I want to correct that.