My kids use my PC with me. They enjoy the game. However they sometimes login to my world and wipe out all the work I have done. Is there a way to password protect or otherwise protect my world from them?
The Meaning of Life, the Universe, and Everything.
You can give each child their own ".minecraft" folder, so their saves will be in their own folder and they cannot go into each others worlds. A good way to do this is to go to the launch options tab, find the configuration you want to change, tick the game directory button, and change the directory to any (preferably empty) folder. You can assign each child to their own configuration by clicking the "Add new" button, and setting it to a different folder for each configuration.
Creating a Minecraft profile for "kids" and changing the location is probably the easiest way,
But creating Windows user accounts would also work, and might be good, to give them each their own workspace for everything (such as bookmarks, text files, etc.) - and it also allows more control, for example access to files or being able to install applications.
The OP didn't say which operating system, but if it's Windows 10, it's easy - in settings, accounts;
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.