Step-1:- Navigate to -> Start -> Control Pannel -> Regional and Language Option -> Click on Customize -> Go to TIME Tab -> Change AM symbol and PM symbol from AM and PM to ur name -> Apply -> Ok
Did It change? If not, follow step-2 below.
Step2:- Now go to time in taskbar and Double Click it to open "Date and time property" ...Look place where time changes in digital form i.e. 02:47:52 AM , click to arrow to cnage the AM or PM by selecting and press arrow. It will Show ur name or name that was entered, Apply -> OK