How can I change or update the “Initials” field in Azure AD?

I found a solution by using ALT+0160 to seperate double surname.
"Max Muster[ALT+0160]Mann" instead of "Max Muster Mann"

see: https://maxdorf.com/article/ascii-characters

Unfortunately, as per https://learn.microsoft.com/en-us/graph/api/resources/user?view=graph-rest-1.0 , there is no "Initials" field in Microsoft Entra ID when you are cloud-only. The "Initials" attribute exists only in on-premises Active Directory. If your environment does not use on-prem AD and does not use synchronization, then the attribute does not exist in your tenant and cannot be added through the Entra ID user properties, Microsoft 365 Admin Center, or standard Microsoft Graph user attributes.

Microsoft services such as Microsoft Teams do not use an Initials attribute even when it exists. Instead, the displayed initials are calculated automatically from the user’s name fields. The order used is:

Given Name

Surname

Display Name

If the initials shown in Teams are incorrect, the only supported method is to adjust one or more of those name fields.

If you need to store initials for some internal purpose, you can add a custom directory extension attribute via Microsoft Graph or an Enterprise Application registration. However, Microsoft Teams and other Microsoft 365 applications will not read or display that custom attribute, so it will not affect what users see in Teams.

Effectively:

• The Initials attribute is not present in Entra ID cloud-only.
• It cannot be enabled.
• Teams derives initials from the user’s name, not from any stored "Initials" field.
• To change initials in Teams, modify the name fields (Given Name, Surname, Display Name).

More at https://learn.microsoft.com/en-us/graph/api/resources/user?view=graph-rest-1.0

If the above response helps answer your question, remember to "Accept Answer" so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.

hth

Marcin