Changes to the "auto-detected" kits (i.e. in qtcreator_install/share/qtcreator/QtProject/qtcreator or Qt\ Creator.app/Contents/Resources/QtProject/qtcreator) do not make it through to Qt Creator.
1. install e.g. Qt Creator from the qt5 installers, these register qt5 and a kit
2. start Qt Creator
3. close Qt Creator
4. edit the registered kit in the install path (either manually or through sdktool)
5. start Qt Creator
Kit has not changed.
(The kit settings are copied to the user config and never updated, why are we doing that again...)