DFF :- Personalizing the flexfield segments is not possible through forms personalization due to below reason:

Personalizing the flexfield segments is not possible through forms personalization due to below reason:

A Flexfield is a single field in a Form but then when you click into it and it opens up the flexfields window, 
the multiple fields you see is actually a user exit with multi segment values, not form fields.
No Form Personalization events are passed to flexfield windows (user exits).
No Form Personalization events are passed to segments inside the flexfield window (user exit).

If you want to disabled the segments, you can disable the segment
in flexfield definition form(Uncheck the enabled checkbox).


The flex developer has stated this would involve a major re-write of the flex code for APPCORE
to process forms personalization rules and actions pertaining to flexfields.
One need to understand that flexfields are not assigned to a canvas, 
the flexfield UIs in forms are not native form fields but built on the fly with user exits.


Defaulting, populating, and or manipulating hidden fields for descriptive
flexfield attributes should not, and are not supported by flexfields to be
done through forms personalizations. Only Flexfields will support through
the flexfield setup and definition.