Thank you for your post.
Do you mean to change it, when someone is submitting a ticket via the customer portal?
Thanks for your answer in advance and have a great day.
Unfortunately, we are currently not able to let the customers change this field.
But we are in contact with the development team to, at least, change this field into "Email address" instead of "Customer".
Thank you for this point. I hope, I could help you with my answer :)