Put a php.ini file inside your root (highest) directory (/home/myusername/) and as it's contents type;
magic_quotes_gpc = Off
worry about making sure all of the other variables are in the file,
they will all fall back to the current server-wide php.ini file, so you
only need to type the variables you want to change.
Or in .htaccess
file within your /public_html/
php_flag magic_quotes_gpc Off