When users edit their profiles, the updated content is also applied to the user information in Kintone Users & System Administration.
If you want to restrict the users who can update the information in custom fields only to Kintone Users & System Administrators, you can configure the setting to forbid users to change the custom fields in their profiles.

1. Click in the header.

2. Click Users & System Administration.
   Accessing Kintone Users & System Administration

3. Click Departments & Users.

4. Click Profile Settings.
   

5. Click of the target field.

6. Clear "Allow users to edit this field".
   

7. Click Save.