I've changed the title without any problems.
I did it on 3 books in a series of 6 when I rebadged the series with new covers.
Before that, I merged a trilogy into an existing series, after I figured out I'd been wrong doing them as 2 trilogies.
I've not tried changing the author name, but I cant see that you can't. But it means changing the metadata, the cover, and the front matter.
You can't do this on paperbacks though. The ISBN registration is fixed. If you change it, it has to get a new ISBN, and that means unpublishing, and publishing again with the new details.
Changing titles always confuses some people who already have the book, so you should include an 'originally published as' statement in the front matter after the copyright statement.
I'm not sure why you'd want to change the author name. The only way that doesn't cause confusion is if the book hasn't sold any copies so far.