Username change - Admin Console - not working

Hello @zakaria_4442, 

Thank you for reaching out.

Does the user whose information you are attempting to modify have a Federated ID or an Adobe ID?  

To verify the type of identity (Enterprise ID, Federated ID, Adobe ID), please check in the Admin Console under the Users tab. If the user possesses an Adobe ID, instruct them to change their name at https://adobe.ly/3XR809R.

If it is a Federated ID, have you followed the instructions in the document linked here to update the username: https://adobe.ly/43SJbhi;

Furthermore, please ensure that there are no duplicate IDs for the customer whose name you are trying to update, as duplicate accounts may lead to account conflicts.