This tutorial will teach you how to change your system time from 24 hour to 12 hour. For example, instead of saying 13:00, your computer will say 01:00 PM. This can make telling the time a lot easier without having to really work anything out!
First of all, Click Start and then click on Control Panel.
In the Control Panel (And this is with the Category View) click on Date, Time, Language and Regional Options.
After clicking that, click on Change the format of numbers, dates and times.
A box will pop up, click on the Customise Button next to the drop-down menu of formats according to their country.
Another box should appear. Click on the Time tab. If your system is already running using 24 hour time, in the Time format box there should be HH:mm:ss. The two Capital H's make the clock use 24 hour. To change this, replace the Capital H's with small h's. So, you should have changed the format from HH:mm:ss to hh:mm:ss. Now, that's fine and dandy, but you might want it to say either PM or AM at the end. To make this happen, add two small t's at the end of the format. So, the format code should now be hh:mm:ss tt.
Click on OK. And now click Apply in the Regional and Language Options box, and then click OK again.
Hopefully your time in the system tray should be in 12 hour. For example, your clock should not be saying 13:00 or 16:00 anymore, but should be saying 01:00 PM or 04:00 PM respectively.
I hope that this tutorial helps!