Why can't I enable allow_url_fopen or mysqli.allow_local_infile in a user-level php.ini file?
These options, along with many others, belong to a group of options that fall under "PHP_INI_SYSTEM" which means that the system level php.ini controls them.
For a full list of these directives, see the list at php.net.
To make changes to PHP_INI_SYSTEM settings, use WHM > Software > MultiPHP INI Editor.
If you manually edited the php.ini file only, you might not be seeing your changes reflected because the PHP handler in use makes use of .user.ini or .htaccess files instead. For more, read the MultiPHP INI editor documentation
Use the cPanel > Software > MultiPHP INI editor to save you php.ini edits to ensure that the PHP handler loads them/