Players which have joined another's game via local area connection or Xbox Live can modify the following fields in the new "world settings" tab under the Settings: difficulty, toggling of cheats, toggling of "always day", and their own personal gamemode.

When modifying the difficulty, nothing happens.

When enabling cheats, the joined player will appear to have access to commands, but attempting to do any of these will result in a failure and the message "Cheats are not enabled on this level."

If the joined player modifies the "always day" toggle, then the time will briefly switch to daytime, but after a few seconds it will revert back to the original time. This only happens on that device, no one else's time is effected.

I have not tested the result of changing their personal gamemode.

Basically, any changes made are client-only and do not affect the other connected players.

Solution: Gray these four options out just as the seed and level name are grayed out. If the joined player is made OP, then these will be ungrayed and they will be able to modify these.

A search was performed for this issue using the keywords: "Multiplayer Cheats". One report came up, but it had been created on September 3 and had no interaction. It was also very brief and undescriptive. I concluded that a new report with better documentation would be better.