When you create a QML project in Qt Creator, in the "Projects" view there is a default "QML Viewer" run configuration and a Add->Run QML Script option.

However, if you create or import an existing C++ project that also has some QML files, there's no longer any easy way to get a QML viewer run configuration for testing or debugging. I would propose that you always have the Add->Run QML Script option available, in addition to the current Run->Custom Executable, for every project type.