i am using PHP Version 4.3.2 on unix server. could you''l provide the
link which describes all the directives for version 4.3.2 with an
explanation of what each directive default value should be and how to
change these default values.

You're referring to /etc/php.ini, no? If you are root on this server, you'll have no issues, however most shared server configurations do not allow you access to this file for security purposes. If you do have write permissions, you won't have any issues. Well, if you haven't already seen them...

http://us2.php.net/ini.core

Most of the configuration settings will be explained in "comments" above the directives. In order to enable a directive you must remove the ; before it.