Start a new world and set the game mode to Survival
Turn off Cheats before creating the world
Do not enable Creative Mode in the world settings
Avoid using commands that can switch game modes
Do not open the world to LAN or any multiplayer setup that allows admin changes
On devices with file access, do not edit the world files to re-enable cheats or creative mode
Use a world template or preset that locks the game mode to Survival if available
Back up the world so you can restore it if the mode changes accidentally