Drupal 8 Form with permissions

Thanks to the Drupal community, I was able to create a Drupal 8 form and actually get it to work!

WIth that done, I went onto my site as an anonymous user and was able to access the form just as I was able to do under my own login.

I have been reading about $module.permissions.yml but I’m not sure if I need a static or dynamic file.

What is the best and securest way to associate the form with each authenticated user?

Drupal version: 


Source: https://www.drupal.org/taxonomy/term/4/feed