To make your account in cpanel server have custom php.ini for all subfolder You need to use below code steps
1) Login to server via SSH
2) scp /usr/local/lib/php.ini /home/cpanelusername/public_html/
3) vi /home/cpanelusername/public_html/.htaccess
Add below code
suPHP_ConfigPath /home/pankaj12/public_html
<Files php.ini>
order allow,deny
deny from all
</Files>
Once done custom php.ini should be available for all accounts