Issue:

In CyberPanel, the default upload limit for PHP is 2 MB. Attempting to increase this limit does not work, either by editing the vhost, .htaccess, or PHP configuration.

Solution:

The solution is that you need to edit the oldest PHP version, regardless as to what your site is set as, as for some reason CyberPanel will use that value instead.

In this example, the CyberPanel server has PHP 7.1 installed. Edit PHP 7.1 with the desired values and click on "Restart PHP". This value will filter down to all other PHP versions.