Trouble configuring discourse with reverse proxy

Inside the app.yml do I change these ports:

expose:
  - "80:80"   # http
  - "443:443" # https

to something like:

expose:
  - "8000:80"   # http
  - "8080:443" # https

8000 being the port I want it to look for from the main Nginx machine.
It’s the one thing I have in mine and well I tested and doesn’t seem to work. (Rebuilt the Discourse App).