Need help regarding change date for train ticket.

Hello, i have a CNF train ticket on July 10th from x to y place. I want to change the train date to 16. They are 3 change trains. From hyd to vizag(10th jul). Vizag to Puri (on 10th). From bhn to hyd 15th. I want to change these train booking dates, what is the best I can do?