Symfony is a set of reusable PHP components and a PHP framework to build web applications, APIs, microservices and web services.
The configuration file of Symfony framework is parameters.yml. This will be autogenerated during composer install/update. So, the custom variablea added to this file will be overwritten.
Inorder to resolve this problem we need to update the custom variables in parameters.yml.dist. So it will not be overwritten suring composer install/update.