Hi @ندى الربعي
I understand that you are trying to change your display name of your 365 Microsoft account.
1.In the admin center, go to the Users > Active user page.
2.Select your username, and then on the Account tab select Manage contact information.
3.Update the user's name and contact information and click on save changes.
For more information: https://learn.microsoft.com/en-us/microsoft-365/admin/add-users/change-a-user-name-and-email-address?view=o365-worldwide#resolve-error-messages
Hope this helps. Do let us know if you have any further queries.
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Thanks,
B. Siri Chandana.