Why is there only one name stated on my ticket?

Some tickets (for example, German/DB tickets) are sold as one ticket for your entire group, meaning only one name is mentioned. Your ticket does however state the number of travelers for whom the ticket is valid. You can therefore travel with this amount of and scan the ticket several times at the check-in gate. 

Unfortunately, it's not possible to change the name on the ticket. The system automatically selects the name of the passenger entered first.