Cannot change Owner (Leads, Potentials, Contacts, etc)

Cannot change Owner (Leads, Potentials, Contacts, etc)

When I click on NEW on any tab (Task, Leads, Potentials, Accounts, etc) it shows always the same owner (one of our users) in ALL of our users. We have 5 paying licenses, and we are all seeing the same owner. Please respond.
Luis Zambrano