How do I set up python 3 on Cygwin on Win 8 platform? I've tried running the set up again but the same version of Python 2 persists.

Have you tried watching/searching for the where the software was installed and put that in your PATH? I have had the same problem running multiple versions of Python on Linux....

HTH

How do you do that?

The install package or script should have documentation or a command line option specifyign where it installs the new version of Python. Simply add that to your $PATH environment variable -- in bash, this is done via:

export PATH=/directory/containing/python3:$PATH

If a special lbirary directory is needed, you might need to add it to your $LD_LIBRARY_PATH in a similar fashion.

You might want to read some basic documentation on the bash shell (command interpreter). If you're new to Cygwin and *nix-like environments, it will help you a lot.

I did that but the version of Python when I do 'python -V' is still python 2.

What happens if you try the "python3" command instead of "python"?

It says that python3 is not a command.