How to enable and disable the PHP register_globals directive?

When the register_globals directive is enabled, PHP creates variables 
automatically from HTML form parameters and cookie data. 
To enable this functionality, use a text editor to modify the 
register_globals directive in the php.ini file as follows:

register_globals = on

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

register_globals = off

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