You can not edit php.ini in your account.
However, via your .htaccess file, you can enter a plurality of settings. See the most common examples below. Remember that the following memory limit is the case for the respective account:
Silver Package: 128MB
Gold Packages: 256MB
Platinum Packages: 512MB
To view the error message on its page:
php_flag display_errors on
php_flag display_startup_errors on
php_value error_reporting 2047
Upload restriction:
php_value post_max_size 16M
php_value upload_max_filesize 16M
PHP memory:
php_value memory_limit 128M
Keep in mind that fake parameters or users may cause the site to be interrupted.