Hi Max ... your English is better than my Italian.
If your live view is too dark or too bright, the cause may be that the camera is set to under-expose or over-expose.
To check, look in the upper part of the screen where it shows camera information.
Look for the number under EV. It should be close to zero.
If it gets set to -2.0 or -3.0, that will underexpose photos by 2 or 3 stops and make the live view too dark.
If it gets set to +2.0 or +3.0, that will overexpose photos by 2 or 3 stops and make the live view too bright.
Use the right thumbwheel on the controller to dial it back to zero or close to zero.