You can control which fields staff use to search for customers. Add and remove fields from the customer search on the Customer Configuration page.
Go to Population Settings > Configuration.
In the Customer Field Settings section, find the field that you want to add to or remove from the customer search.
Click Show in Customer Search for that field.
Note: If the Show in Customer Search checkbox is disabled for a field, then it is not possible to add that field to or remove it from the customer search.
Click Submit.