After you have compiled or installed PHP, you can still change its behavior with the php.ini file. On Unix systems, the default location for this file is /usr/local/php/lib, or the lib subdirectory of the PHP installation location you used at configuration time. On a Windows system, this file should be in the Windows directory.
Directives in the php.ini file come in two forms: values and flags. Value directives take the form of a directive name and a value separated by an equals sign. Possible values vary from directive to directive. Flag directives take the form of a directive name and a positive or negative term separated by an equals sign. Positive terms include 1, On, Yes, and True. Negative terms include 0, Off, No, and False. Whitespace is ignored.
You can change your php.ini settings at any time, but after you do, you'll need to restart the server for the changes to take effect. At some point, take time to read through the php.ini file on your own, to see the types of things that can be configured.