Did they change how often you need your passkey when you change account settings?

Hello Trevor,

A stated above, you would not receive any sort of notification every time you sign in to your own console. Signing into a new console would prompt for a password, so you wouldn't need to worry there. If you are concerned about people using your account in
your home, consider either adding a passkey to your account or changing the password.

Create and manage Xbox one passkey

How to change Microsoft account password

Hope this helps!

Hi nickstanton2,

Thanks for reaching out to us in the forums with this issue. In relation to any changes made to a Gamertag, if you've already used your initial complimentary change, then any further changes made would need to purchased. This means that even if you were
game sharing with someone and they made the change, in order to change the Gamertag to something different you would need to pay the fee (which varies by region). Please also bear in mind that when game sharing, your profile need not be logged in and that
you should never share your password with anyone in order to keep your account safe.

How to change your Xbox gamertag

Gamertag update FAQ

To prevent occurrences like this in future, I recommend that you create a passkey on your accountso that any further changes to your account cannot be made. Here are a couple of support articles that you may find useful for keeping your account safe when
game sharing:

Require a passkey for purchases on your Xbox One console

Create an Xbox One passkey

I hope that this information helps you out. Let us know if you have any further questions.

you can also set your account to Lock Down so it requires your password or you can set it to require Passkey before any settings can be changed and before purchases can be made.

how to Lock Down your account or request a Passkey

how to set your Passkey

hope this helps

What Passkey option did you set? If you set a custom sign-in option that included "Don't ask, just sign me in; Ask for passkey for: Purchases, Changing my settings" then that may be how your friend can still log into your account without the passkey. Alternatively,
maybe you set a Passkey that is too short or easy (eg mine is a 6 button combination) or your friend saw you use it.

Yeah unfortunately you used your free change when your brother changed it. On top of password change I would put a passkey on your account that only you know.