keyboard IT US

Where did you get this machine? The keyboard is non-standard. It has the Italian keys but has the ANSI/US physical format. Apple does not make that, so no layout will fit it right. It should be ISO/European, with an extra key next to z and a vertical enter key, like below. If you can return it, you should do so. Otherwise it may be necessary to make a custom keyboard for it with Ukelele.

Even if you manage to set the desired configuration via software, the keyboard itself is not going to look any different. You'd just have to remember what keys are assigned what function.

If you need the KB to actually be a different one physically, you needed to have bought the one needed.