How do I change the default python version for my pyenv user environment?

hoodedvul

Also see:
pyenv help
How do I install the python multiple version management tool pyenv?

Version before changing the global python version. This is system.

$ pyenv versions
* system (set by /home/trainer/.pyenv/version)
  2.7.15
  3.8.5
  3.8-dev

Change the default global python version using pyenv.

$ pyenv global 3.8.5

Check the global version of python now.

$ pyenv versions
  system
  2.7.15
* 3.8.5 (set by /home/trainer/.pyenv/version)
  3.8-dev

Note: Changing the global version applies to your own user environment. It does not modify the operating system version.