title: Installed Python 3.9.1 onto MAC OS but still says Python version is 2.7
body: <p>I installed Python 3.9.1 onto my MacBook however when I use the command python --version it says its python 2.7. Here's what going on in my terminal for reference:</p>
  <pre><code>$ python -V
  Python 2.7.16
  $ brew install pyenv
  Updating Homebrew...
  ==&gt; Auto-updated Homebrew!
  Updated Homebrew from 565becc90 to e41981a5c.
  Updated 1 tap (homebrew/core).
  ==&gt; New Formulae
  htmltest                   mpdecimal                  vitess
  ==&gt; Updated Formulae
  Updated 158 formulae.
  
  ==&gt; Homebrew was updated to version 2.7.7
  The changelog can be found at:
    https://github.com/Homebrew/brew/releases/tag/2.7.7
  Warning: pyenv 1.2.22 is already installed and up-to-date.
  To reinstall 1.2.22, run:
    brew reinstall pyenv
  $ pyenv install 3.9.1
  python-build: use openssl@1.1 from homebrew
  python-build: use readline from homebrew
  Downloading Python-3.9.1.tar.xz...
  -&gt; https://www.python.org/ftp/python/3.9.1/Python-3.9.1.tar.xz
  Installing Python-3.9.1...
  python-build: use readline from homebrew
  python-build: use zlib from xcode sdk
         
  Installed Python-3.9.1 to /Users/myname/.pyenv/versions/3.9.1
  
  $ 
  $ python --version
  Python 2.7.16
  </code></pre>
  <p>Thanks in advance for your help!</p>