Hi Nguyen,
Thank you for contacting the Microsoft Community.
I fully understand how important it is for your legal name to match your valid ID to prevent any issues when you take the exam. I’ll proceed with the update right away to ensure everything is correct.
For me to verify your account and input the necessary changes, kindly provide me with the information I requested through the private message I initiated. For your reference in locating, please check the below image:

On the other hand, if in case you have a scheduled exam, it is best to reach out to Pearson VUE for immediate assistance with rescheduling options and other recommendations while we update your legal name. Pearson VUE can access your exam details and check the situation. Their website offers the option to contact them via a live phone call for real-time assistance. You can select your region to see all the available support in your area. Additionally, they have introduced a feature that allows you to speak with an agent through live chat.
Your cooperation is appreciated and know that we are here to support you every step of the way.
I look forward to your response. Please note that if no response is received after two business days, the case will be closed and locked. After the case is locked, we will no longer be able to respond, even through Private Messages. Thank you.
Kind regards,