When creating a new person in System Administration, you can add a Person ID, or you can opt to choose from an auto-generated Person ID that mirrors the user's email address.
If a Person ID needs to be updated (or the auto-generated version was inadvertently created). the Person ID can be updated via import in System Administration.
From the People section of System Administration, click on the Import Data button on the top right and select Import People.
If there is an existing People file, only the "person_id" field needs to be updated to the intended ID. Otherwise, the available template can be filled out with the users existing information with the updated ID can be imported.
Once the file is ready, click Browse to Select File and select the file that will be imported.