How to enable and disable the PHP allow_url_fopen directive?

To enable this functionality, use a text editor to modify 
the allow_url_fopen directive in the php.ini file as follows:

allow_url_fopen = on

To disable this functionality, modify the allow_url_fopen 
directive in the php.ini file as follows:

allow_url_fopen = off

How to change the maximum number of input variables for PHP scripts?

PHP obtains input variables from HTML forms (through GET and POST requests), 
as well as from any cookies enabled on a page. 
By default, the maximum number of input variables allowed for 
PHP scripts is set to 1000. You can change this amount by 
adding the max_input_vars directive to a php.ini file.

To change the maximum number of input variables allowed, use a text editor
 to add the max_input_vars directive to your php.ini file. For example,
 to set the maximum number of input variables to 1500, add the following setting:

max_input_vars = 1500

How to enable and disable the expose_php directive?

When the expose_php directive is enabled, PHP includes the following line in 
the HTTP response header when a PHP page is requested 
(the exact version number may differ depending on your configuration):

X-Powered-By: PHP/5.3.27

By default, the expose_php directive is enabled. However, you may not want to 
broadcast the specific PHP version your site is using. Similarly, 
some third-party applications require the expose_php directive to be disabled.

To disable the expose_php directive, use a text editor to modify your php.ini file as follows:

expose_php = off

With the expose_php directive disabled, PHP will not send the X-Powered-By header. 
To re-enable the expose_php directive and send the X-Powered-By header, 
modify your php.ini file as follows:

expose_php = on