Facebook changes order of profile pictures?

[Exabyte]

That's because you can't.
It arranges the pictures by the order you've set each picture as your profile picture.

For example: Profile Picture #1, #2, #3.
3 being your current profile picture, it would appear first (from the left), followed by the previous one (#2) and the one before that (#1). etc. In short, your profile pictures would show from the newest to the oldest.

Please note that this behavior applies to your "Cover Photos" album too (assuming you're using Facebook timeline).