Gameplay questions should be asked in the General forum, this is for hardware support.
But the answer is:
There is a button on the main screen where you pick your scenario.
It is called Options, click it and the top option is dificulty level, click that work and you can select from the popup radio buttons whch difficulty level you want.
But the answer is:
There is a button on the main screen where you pick your scenario.
It is called Options, click it and the top option is dificulty level, click that work and you can select from the popup radio buttons whch difficulty level you want.