Hi @TorresJulie,
Welcome to Microsoft Q&A, and thank you very much for reaching on to us.
Based on your description, I tested this in my environment and confirmed that you can change the username or image without altering the user’s avatar. Here’s how you can do it:
Go to Settings > Account and select the desired account.
On the account page, click Show as, then select Customize.
From here, you can choose a color preset for the account or icon. If you want to make further adjustments (such as text or icon), click Edit.
I hope this helps. If you have any questions or need further clarification, please let me know. I’d be happy to assist you further.
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