A custom field does not appear in the Custom Fields tab of the Task Information dialog or the Resource Information dialog until it has been renamed using this procedure. If you want a field to appear in these dialogs, make sure you rename it.
Renaming a Field
Click Tools, Customize, Fields from the menu bar.
Select the type of field you want to rename by selecting the field type from the Type list.
Select the field you want to rename.
Click the Rename button.
Enter a new name .
The field is renamed, and the new name appears in the dialog with the old default name in parentheses.