If you need changing any details on OCI, you must fill up the online form and submit to nearest embassy / consulate.
The message is intended for the fact that if you got a new passport, you needn't apply for OCI as you can carry new + old passport + OCI card.
Please clarify further with OCI section. For London, contact:email@example.com
For OCI Unit - Delhi, contact: firstname.lastname@example.org