Adding a field - Accounts Page (Contacts section)

Adding a field - Accounts Page (Contacts section)

Hi 
In the Contacts section on the Accounts page it shows a few fields (Contact Name, Email, Phone, Mobile)
How do I add the "Title" field after the "Contact Name" field?
(I went to Setup/Customize/Modules/Accounts - but it didn't show Contacts on the layout)
Thanks
Ross