Session Cookie Name and Timeout in Symfony

In apps/frontend or backend or other/config/factories.yml... put this to the all section:

  user:
    class: myUser
    param:
      timeout: 43200
          
  storage:
    class: sfSessionStorage
    param:
      session_name: frontend

Don't forget to clear the cache and set the value of session.gc_maxlifetime to the same or a bit higher than 43200 in php.ini.