setDefaultFormat value is forgotten

int main(int argc, char *argv[]){
	QSurfaceFormat sf = QSurfaceFormat();
	sf.setRenderableType(QSurfaceFormat::OpenGL);
	sf.setProfile(QSurfaceFormat::CoreProfile);
	sf.setVersion(4, 3);
	sf.setSamples(8);
	QSurfaceFormat::setDefaultFormat(sf);
	QApplication a(argc, argv);
	MainWindow w;
	w.show();
	return a.exec();
}

	if (glVieweverMaximized){
		ui->openGLWidget->setParent(ui->frame);
		ui->horizontalLayout_8->addWidget(ui->openGLWidget);
		ui->openGLWidget->show();
	}else{
		ui->openGLWidget->setParent(nullptr);
		ui->openGLWidget->show();
	}
	glVieweverMaximized=!glVieweverMaximized;