Setting up date and time on iPhone 6 and other iPhones is really simple. You may also use the 24-hour format or go for the automatic setup base on your time zone. To set date and time on iPhone and iPad and iPod touch devices running iOS 9 or later, do as follows:
1. Open the Settings from the home screen
2. Go to the General settings
3. Scroll almost all the way down and tap the Date & Time settings
4. Toggle off/on the 24-hour Time, to choose between 10:00PM and 22:00
5. To manually set date and time on iPhone, make sure the Set Automatically option is disabled.
6. Change the Time Zone, date and Time based on the current date and time.