If you have booked one of those cheap econ ticket with no change allowed, I would say theres only a 1 in 1,000 chance you are able to change your connecting flight (unless your ticketed flight has been cancelled by the airline).

MH today is very different from a couple of years ago, they are very strict in adhering to the terms and conditions attached to the fares and are extremely revenue driven looking for every opportunity to add on charges. To give you an example, one of their Regional Managers rescinded on her word to upgrade me (to make up for to an inconvenience) when HQ wasnt happy with the fare I paid.