How do you change the date format?

From Joomla! Documentation

The "J1.5" namespace is an archived namespace. This page contains information for a Joomla! version which is no longer supported. It exists only as a historical reference, it will not be improved and its content may be incomplete and/or contain broken links.

The date format information for Joomla! 1.5 is stored in the file <Joomla! home>/language/<your language>/<your language>.ini. For example, for English, it is <Joomla! home>/en-GB/en-GB.ini.

To change the date format, find and edit the values "DATE_FORMAT_LCx". By default, the date is in international format (for example, Thursday, 31 January 2008 18:30). To change to standard US format (for example, Thursday, January 31, 2008, 06:30 PM), make the following changes:

DATE_FORMAT_LC2=%A, %B %d, %Y %I:%M %p
%A, %B %E=%A, %B %e

These are the formats for the time...

%H:%M = 00:00 through 23:59
%k:%M = 0:00 through 23:59
%I:%M %P = 00:00 am through 23:59 pm (I = upercase i)
%l:%M %P= 0:00 am through 23:59 pm (l = lowercase L)

(Note that %P will print the lowercase am/pm indicator for your locale, which may be blank.)

%I:%M %p = 00:00 AM through 23:59 PM (I = upercase i)
%l:%M %p= 0:00 AM through 23:59 PM (l = lowercase L)

...and for the day

d - Day of the month, two digits with leading zeros - 01 to 21
D - Day in text, three letters - Sun through Sat
j - Day of the month, one or two digits without leading zeros - 1 to 31
l (lowercase L) - Day in text, complete word - Sunday through Saturday

Joomla! uses standard Linux date format codes. A complete reference is avaialable in the PHP Manual.