On line 277 of the php.ini file, "display_errors = On" is already enabled by default.
Just make to sure to have this php.ini file in any directory where you are running php scripts.
Or, you can enable PHP5 (FastCGI) from the PHP Config icon, and then you'll only need the one
located at public_html/php.ini.
Keywords: PHP display_errors php.ini display errors