Allow users to edit core fields

Changes you make to custom fields do not appear on custom pages until your next login. Similarly, users who are logged in when you make changes to custom fields do not see those changes until they log out and log in again.

To allow users to edit a core field:

From Administration>Custom Pages, identify the page(s) that contain the core field you want to make "editable." Highlight the page and click Edit. The Edit Custom Pages screen appears.
Is the list too long? You can filter the list with the Filter and Contains fields up above. More info... You can also sort the list by any column. More info..
Find the Field name. If the page you are modifying is a page on which edits are possible, you have the option to make the field an Editable field. If you want the field you are adding to be editable on this page, check the box for Editable.
Click OK . To see your changes, log out, and log back in.

Only users who have permission to modify the page you are editing will have permission to edit a field you make editable.