The only details provided during your account creation that you can change on your own are:
Username
Phone number
Be careful that there are limits to how often you can change these details. After exhausting these limits, you must contact the customer support team to change them.
The details provided during your account creation that you cannot change on your own are:
First name
Last name
Email address
If you want to proceed with any change, you will need to contact the support team via email or chat. If the reasoning is not clear enough, the request might be denied.