Comment # 1 on bug 985557 from Walther Pelser

"-qwindowtitle, sets the title of the first window."  
Taken from 
            http://doc.qt.io/qt-5/qguiapplication.html
Seems, that it sets the title ONLY of the first window.

I found something like

this->setWindowTitle("New Title");

But qt is not my favored language, in fact I can't.