In Minecraft, my son can't get saved worlds to open?

When he logs in and is using creative mode, there's a scrollable list of saved worlds he created stuff in and it says to select one to open. But they don't appear to be live links or clickable. Just static. So he ends up having to create new worlds.
Anyone know how to fix this? Or what is wrong?

You hit the "Play selected world" button after selecting the world, right?

Is it downloaded to your computer?