I want to change the username on my MacBook Air

Hi everybody,

I´m kinda new to the apple community. I just bought a MacBook Air, I signed in with my existing Apple-ID, when setting up my MacBook I was asked to choose a username, I choose Eveline82 (like here on the community page). On my Apple-ID I was registered with my old name Eveline S. but my legal name now is Eveline F., so I changed my name and email address on my Apple ID but it didn´t change my name on my computer, where I´m still Eveline S.

I really don´t want to see that old name of mine. Seems to me like this was pre programmed into my MacBook Air when I purchased it. How can I change this?

Please I need help. I was trying to find an email for support but online I only found a way to call technical support but this issue is not technical so I´m a bit lost here on who could help me.

Thank you so much for any help.

Eveline