To export to Android in release mode, you need to do two things:
- Configure a release keystore in the Android export preset. The debug keystore configured in the Editor Settings won't be used when exporting in release mode.
- After clicking Export Project in the export preset dialog, in the file dialog, uncheck Export With Debug at the bottom of the file dialog before exporting the project.
if debug on, people can cheat in the game right.
Not really. Cheating in a singleplayer game exported in release mode is still possible by various means, and there is no way to fully prevent it. In a multiplayer game, it's still possible if the server isn't authoritative.