How to customize DateTime format with AM or PM with Sharepoint 2010

1. I would like to display a datetime format with AM or PM. I have tried with hh:mm:ss tt or hh:mm tt or hh:mm zz but it didn't work, it just display the time as 09:00 tt or 09:30 zz. Please give me some advice to address my problem.

It must be like this 01:30 PM or 09:00:30 AM

2. Besides with that current format, I am not sure that it is correct or not. I tried to update some documents at 09:00 AM but it displayed at 01:00...