I am not aware of any customization you can do. The current address book will be completely replaced with the next version of Thunderbird (78). Bug 841598 and it's dependencies.

Perhaps the cardbook addon would meet your needs until then, or permanently. https://addons.thunderbird.net/en-US/thunderbird/addon/cardbook/?src=ss

Personally I still use the windows contacts (Wndows key + R, type contact and press enter. The summary in Windows contacts appears to be what you want. It does not look that way in Thunderbird, but really I only use the address book as an address list when addressing mail, and it makes synchronizing contacts with the phone easier.

I have instructions here to integrate the windows contacts into Thunderbird. https://thunderbirdtweaks.blogspot.com/2013/12/windows-contacts.html

Note contacts and people are two different things. People is basically the contacts from outlook.com which integrate via the TB sync addon from outlook.com

Matt,

I guess I will wait for the new version of the address book with the next release. I would only like a few categories/columns in my contact card (like second name, first name, email, organisation, phone etc.). But I would also prefer 2 or 3 custom categories (maybe a + sign to add as many as custom categories as one wants) which one can add depending on his needs. Currently the information on cards is all scattered with multiple tables and when we export it to a csv file, there are like so many empty columns which no one needs. A few columns in a csv file is more easy to comprehend.

Regards,

LS