In case the qtcreator.ini has a TextEditor section without a defined ColorScheme value...

[TextEditor]
FontZoom=90

...Qt Creator decides to create a new "styles/customized%i.xml" and select that as scheme.

I find this confusing, since I don't know what purpose this feature has in the current state of Qt Creator. I assume that this was implemented way back then, as migration code when selectable Color Schemes were introduced.

Code: http://code.qt.io/cgit/qt-creator/qt-creator.git/tree/src/plugins/texteditor/fontsettingspage.cpp?h=3.6#n210

This makes implementation of QTCREATORBUG-15229 uglier. If we don't remember what this was for, I suggest removing that "Save it as a color scheme file" part.