If you want to change the default port number so when you run the "runserver" command you start with your preferred port do this:
Find your python installation. (you can have multiple pythons installed and you can have your virtual environment version as well so make sure you find the right one)
Inside the python folder locate the site-packages folder. Inside that you will find your django installation
Open the django folder-> core -> management -> commands
Inside the commands folder open up the runserver.py script with a text editor
Find the DEFAULT_PORT field. it is equal to 8000 by default. Change it to whatever you likeDEFAULT_PORT = "8080"
Restart your server: python manage.py runserver and see that it uses your set port number
It works with python 2.7 but it should work with newer versions of python as well. Good luck