QSettings settings("MyCompany", "MyApplication");

// if the app has been deployed, the settings are missing so this returns false. If the app is restarted, this returns true.
bool runOnce = settings.value("runOnce", QVariant(false)).toBool();

if(!runOnce)
{
    // re-create the necessary settings values since the settings are missing
    settings.setValue("Greeting", "Hello");
    // mark the application as having run already.
    settings.setValue("runOnce", true);
}

qDebug() << settings.fileName(); // "/data/data/org.qtproject.example.myapplication/files/.config/MyCompany/MyApplication.conf"

qDebug() << settings.value("Greeting").toString(); // "Hello"
qDebug() << settings.value("runOnce").toBool(); // true