How to change time on iPhone
Go to Settings -> General -> Date and Time. 

Here you have several options:


Set Automatically - this sets the time to the time of the region you are currently in. Allow your device to use its current location to determine the correct time zone. To do this, go to Settings > Privacy > Location Services > System Services and select Setting Time Zone.
Time Zone - here you can manually select the region you are in and our time will adjust
24 Hour Time - this changes the time between 24 hour and 12 hour time