the configuration file and the skins are explicitly *not* upgraded when you upgrade weewx
this is to reduce the chance of breaking anything, and to let you choose to upgrade them only if you want to
in the case of the config file, there is almost never a need to upgrade it. when new features are added to weewx, they have sane defaults.
in the case of skins, you only need to upgrade if a specific skin has new features/functionality that you want, and then only when you are confident that upgrading the skin will not break your customizations (if any)
m