Some versions back the *name* of the relevant variable was changed from PPP_CONFIG_DIR to SATPY_CONFIG_PATH.
That's all. Before starting a script in the black window this variable must be known. Under GNU/Linux I issue the command
and it says
Under Windows the command (with default install as in the HOWTO 3.0)
I do not see why my instructions should not work for the new name of this variable under Windows.
Just configure an environment variable with this name (and delete the old environment variable).
With satpy.config.set() and satpy.config.get() you leave the comfort zone of most Windows users.