Help me with my Xbox?

I have a question I changed my Microsoft account and wanted to change that on my Xbox 360 too, but how should I do that if I can't go to "Account" in Settings? I don't understand somehow can someone help me?

Do you have an internet connection?

Would also be my first question. Looks like the questioner isn't connected to the internet.

Can I register with XBox here?

Yes I have

So you want to sign in with a new Microsoft account?

You do this in the login screen when selecting a profile. You can add a new profile there.

The fact that the windows are grayed out in your picture is logical because you are not logged in with any profile.