You are using phpFox version earlier than 4.6.0? Please refer instruction for this article here.
There are many times when you will want to find a specific user in your AdminCP user manager. This will show you how to do that. This assumes you are already logged in as the Admin user and are logged into the AdminCP.
Go to Members then Select Browse Members.
Once you see the user list, you can search for users by using the search box on top. This box allows filtering searches including custom fields. We will just show a small portion of the advanced search box. Click the View More Search option to see all the available search filter options.