App loaded without installing in site

I’ve a custom app called “meeting” inside frappe-bench/apps directory. This app is installed in site “meeting.localhost”. I also created another custom app “library_management” inside frappe-bench/apps directory. I am trying to create a new site “library.localhost” and install only the “library_management” app in this site. But all of the apps is loaded in all sites. What is the purpose of install app if all apps inside frappe-bench/apps automatically gets loaded in all sites?

Have you followed this way ?

bench --site meeting.localhost install-app meeting 
bench --site meeting.localhost remove-from-installed-apps meeting

after installed and removed migrate is necessory

bench --site meeting.localhost migrate