Contact id field in personalization -how can i find this field under page sources?

Summary

Contact id field in personalization -how can i find this field under page sources?

Content

Hello ,

We would like to change by personalization to option
from mandatory the ‘Contact id’ field , in the ‘Contact’ tab of the ‘personal information’ a screen.
The ‘contact is’ field is the under the ‘create’ and ‘edit’ buttons.
I open the create and edit under ‘view’ mode (not source) -press ok - then replace to ‘source’ mode. And Press edit on the main table - but I can’t find the ‘contact id’ field.

How can I find in the source this field for the personalization?