Game switched to creative mode on its own

My game world moved to the bottom of list, this should have been in the top of the list (I just closed this world), also the name of the world was gone. When I opened Minecraft the game was in creative mode on its own. I am the only person that uses this computer. I have made no changes to this computer, which I know about, Windows 10 users no longer have control of when updates happen.

After some expermentation the same thing happens if I open the the level.dat file and make changes to it.