To my pleasure I discovered that I could add fields to the form view of a contact record using Tools | Forms | Design this form.
First problem: I couldn’t see how to get out of the ‘design’ mode and, when I somehow managed this feat, (second problem) the form was unchanged for all other data records in that (and all other) sub-folders of Contacts.
I’m obviously making some wrong assumption(s), but I haven’t the faintest idea what they are.
Help, please!