Trixie, to re-phrase what Rick wrote, posts ARE displayed in descending order: Earliest at the top, and latest (newest) at the bottom.
And that IS ascending order (I realize that seems reversed, but it is not... if you have multiple posts with different dates, ascending order is:
May 1
May 2
May 3
...
May 25
The number in the date gets bigger as you go down.
And as Rick said, you cannot change that.