Hi Mandeep,
You can make a field read-only on a qListForm by setting the field property "Field Type" (ezEdit->DisplayFields->Edit field and scroll to the bottom of the dialog).
Let's say that you come to the qListForm from a qListView, then on a qListView set the session and on the qListForm Field Type you can set the property to "Consume value from a session" and provide the session name and the field name.
Please check the docs for more information about the "Field Type" setting.