Wrong Gamertag / Changing Gamertag (Halo Reach PC Steam)

Had this issue too, my friend just logged in after buying the game and he already had an account. He logged in to his old existing account and it automatically changed his name too. It's stupid

I'm having this issue too. I suspect that their services are overloaded, I tried to change my name from one of their defaults. On most pages on the website it has my new name. But in game it's still the original default name.

I figured it out after remembering how the naming process worked when I was a kid.

Upon the first time launching the game, it will make you create a new Microsoft account and choose a gamertag if you do not have an account. Once loading in, if you see that you have a randomly generated name like I did, follow these steps:

1) Click on the party icon on the top right next to your name to bring up the menu

2) Click on banner and select "Change profile" - this will sign you out

3) Go onto your web browser and log into your account on the Microsoft website and go to Manage Account

4) From here, you should see an option to change your gamertag. They allow you to change your name once if you ended up choosing the randomly generated one (or in most of these cases getting assigned it). Fill out the information to change your gamertag.

5) Once you have changed your gamertag, log into your Microsoft account on Halo and you should see that your name has been updated.

sometimes it takes up to two hours to update our new GT

Its possible that the name you chose was in use already hence it assigning a random name. Also you need to wait 30 days after creating or changing a gamertag/profile before you can change the name again. Here is a link with the information needed Xbox
Live gamertag .

Hope this helps.

Keep Calm and Game On!