The panel clock comes set at a 24-hour clock. If you'd like to change it to a 12-hour clock, here are a few tips...
First, right click on the clock in the panel and choose "Digital Clock" Settings.
You'll change the settings for the clock by changing the code in the first space...next to Clock Format.
Option 1 - A 12-hour clock with a leading zero. Such as 01:30%H:%M
Want to have AM/PM or am/pm after the time? Such as 01:30 PM or 01:30 pm
For capital AM/PM...
%H:%M %p
For lowercase am/pm...
%H:%M %P
Yes...for capital, you use a small p. For lowercase letters, you use a capital P.
Don't ask me why!
Option 2 - A 12-hour clock WITHOUT the leading zero. Such as 1:30%l:%M
(that's a lowercase l ... l as in linux)
And of course you can add the AM/PM. As in 1:30 PM
%l:%M %p
...or the am/pm...as in 1:30 pm
%l:%M %P
There are WAY TOO MANY combinations to list, but I'll give one more...
You want to go completely whack-a-doodle, and have the clock show the time and date...like Windows has on their panel? Okay, but realize you'll either have to make your panel taller, or you may have to reduce the size of your fonts for it to fit!
You know how the Windows clock looks...like this...
1:30 PM
9/3/2016
Though I personally prefer the lowercase am/pm, I'll give the Windows capitalized AM/PM...you know how to change it to lowercase if you want.
%l:%M %p%n%-m/%e/%Y
If you use this, make sure to put a checkmark next to Center text before you close out the Digital Clock Settings window.
Now...if you want to know even more combinations/possibilities, here's a website that makes it pretty easy to find what you want...I wish I had known about it before I figured all this stuff out the hard way.
http://strftime.net/