Trouble importing modules

PyCharm: community edition 2018.1.4

Python: 3.7

I am brand new to PyCharm so bear with me. Why is it that PyCharm can not see my installed modules? For instance, I do a pip install serial and it works on a script in the terminal. Then I go to run the same script in PyCharm and I get an error: 

ImportError: No module named 'serial'

In Settings:(Project:NewProject):Project Interpreter it has Python 3.5 listed as the interpreter and it shows to package's, pip and setuptools.

Do I need to change something in project structure? How do I tell Python where to go look for installed modules? I have looked at some old posts and they all seem to have either been left unresolved or related to a more complex issue.