PHP settings or hosting settings defined in a Service Plan are not changed for subscription after successful synchronization with the service plan
Permissions Hosting settings management and Common PHP settings management are enabled in the service plan.
According to Plesk documentation, Hosting settings management option allows owner managing subscription's web hosting settings. If this permission is granted, then the hosting parameters will not be synced. This means that PHP or Hosting settings on the subscription level have higher priority than on the service plan level.
To make PHP settings to be synced with ones specified in the service plan:
- Login into Plesk and navigate to Service Plans > service_plan_name > Permissions tab
- Uncheck Hosting settings management, Common PHP settings management and PHP version and handler management: