You can either make your changes server wide to your php.ini. Not sure your dist but in debian you would find it at
Code:
/etc/php5/cgi/php.ini
then restart apache2
or if you would like to just make the changes to 1 web
Code:
cp /etc/php5/cgi/php.ini /var/www/web#/php.ini
make your changes
and then in the apache directives for the site add
Code:
suPHP_ConfigPath /var/www/web#/php.ini
you might also have to restart apache2 afterwards