I was playing in a singleplayer world and I checked my toolbars (as in the creative inventory toolbars). In my toolbars, I had a toolbar saved from another world. I don't know why it was there and one world was superflat and the other wasn't. Is this a bug or not?
To download the other ones you need to make a folder in the versions folder for minecraft and put the client and JSON file for the versions in there. They all need to be named the same aside from file extensions. Once you do that, you will be able to choose that version when making a new profile with the minecraft launcher.
Does anyone else have issues crafting items such as chests,hoppers,torches and unable to turn items such as red stone blocks in to dust and diamond blocks back in the diamonds. Please can someone help? I do believe the the update to 1.12 has done this to my game.