Hi Francisco,
You cannot completely change the domain of your Microsoft account from @live.com.mx to @outlook.com, because the domain is part of the original username. What you can do is add an Outlook.com alias to your account and then set that alias as your primary sign‑in address. This way, you’ll log in with the Outlook.com alias going forward, while your original @live.com.mx address remains linked to the same account. It’s important to note that you should not remove the Live.com.mx alias—keeping it ensures you still receive mail sent to that address and maintain continuity with any services tied to it. In short, Outlook.com becomes your main login, but Live.com.mx stays active as a secondary alias so you don’t lose anything.