Cannot update Django to 2.1 I am stuck in 1.11.18

I ran:

pip install -U Django

But because the python default version is restricted to 2.7, I cannot upgrade to Django 2.1 and my django project requires imports unique to django 2 and above.

I have python 3 installed but the default executable path is /usr/bin/python which contains python 2.7

How can I default run python 3 and install Django 2.1 so when I access my site using the IP address given to me, it loads the newest versions instead of defaulting to python 2.7 and consequently Django 1.11.18?

It seems that running a virtualenv requires me to copy all my code into the nano editor, and I can only run a localhost server.

Maybe my issue lies in the fact that I am incorrectly inputting the host IP under the Django settings file.