WordPress is written in the programming language PHP. The date formatting functions in WordPress use PHP’s built-in date formatting functions. You can use the table of date format characters on the PHP website as a reference for building date format strings for use in WordPress.

Armed with this information, I went to my WordPress dashboard and clicked on Appearance and then Editor. Then I started going through the Template Theme files. Sure enough, I found <?php the_time(‘D, m-d-Y’) in the Main Index Template (index.php) file. So I went back to the Format  page to see what options I had and decided on the day, month-date-year for my format. So I changed <?php the_time(‘D, m-d-Y’) to <?php the_time(‘D, m-d-Y’) and then clicked on update. And as you can see, the dates of my posts, on the main page, now have the post date formatted the way I wanted.

The other place you can change the time and date format is in Single Post (single.php) which I did a little different that my main page. I decided to go with l, F jS, Y which will look like: Friday, January 22nd, 2010

UPDATE: I found a couple other places that needed to be changed in my theme. So here is a list of the files that I could change my date format in.

Archives (archive.php)

Comments (comment.php)

Main Index Template (index.php)

Single Post (single.php)

Hope this helps. If you have any questions, leave me a comment and I will try to help.