How to change my user tag from one account to another for use on laptop

each gamertag is associated with an specific account and to use an existing one for you, the other account must change gamertag first

if you want change the gamertag, please follow the steps from this link

https://support.xbox.com/en-US/my-account/manage-gamertag-and-profile/change-xbox-live-gamertag

Hi SuperScubaStar,

You can only sign in to the Xbox app with one Microsoft account at a time. However, you can switch between different Microsoft accounts. To switch to a different Microsoft account:

1. Open the Xbox app.
2. Select Settings.
3. Select Sign Out.
4. Select Sign In.
5. Under Use another account, select Sign in with a different Microsoft account.
6. In the Choose an account window, select the Microsoft account that you want to sign in with.
7. If prompted, enter the credentials associated with that Microsoft account.

Hope this helps and please keep us informed

You can change your tag but you can't transfer from one account to another. There will be a fee for changing your tag if you are not using a system generated tag.

Sorry but this cannot be done. You cannot transfer items from one tag to another. As for changing the gamertag, you could try changing the name of the silver account (a cost of $10) then attempt to change the name of the Gold account (another cost of $10)
to the tag you want. However, be aware that the odds of getting that tag are slim, you got lucky the first time.

Hi there,

You can change the email address associated with an account, but you cannot transfer anything (purchases, achievements, etc.) from one account/tag to another.

The steps to change the email address can be found here.