Expressing that new password is optional
I have built a simple user management system on my webserver. There is a list of users, each of which is either "Administrator" or "Operator". Only administrators can change user details. Below is a screenshot of the "Edit user" modal, based on Bootstrap.
Each of the username, password and rights can be modified. I have opted to leave the "New username" and "New password" fields empty, to mean "Leave unchanged". (I do not want to populate the "New password" field with the actual old password!) As for the "New rights" choice, I have prepopulated it with the old rights.
The "New username" input field is focused when the modal is shown.
I hope the old username is visible enough in the modal title? Have my choices been wise? How would you tweak this modal to make it more usable and clear?
EDIT (using Peter's suggestions)
2nd EDIT (see live example here)