How can i control volume for specific application!!!

I'm about writing code in C++ which i can use to control volume (for example, Google chrome), I added that function to my code, but it control master volume instead of just the application volume:

Code:

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setChangeVolume(const double & iVolume)
  {
      HRESULT hr=NULL;
      double newVolume = iVolume;

      CoInitialize(NULL);
      IMMDeviceEnumerator *deviceEnumerator = NULL;
      hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_INPROC_SERVER,
          __uuidof(IMMDeviceEnumerator), (LPVOID *)&deviceEnumerator);
      IMMDevice *defaultDevice = NULL;

      hr = deviceEnumerator->GetDefaultAudioEndpoint(eRender, eConsole, &defaultDevice);
      deviceEnumerator->Release();
      deviceEnumerator = NULL;

      IAudioEndpointVolume *endpointVolume = NULL;
      hr = defaultDevice->Activate(__uuidof(IAudioEndpointVolume),
          CLSCTX_INPROC_SERVER, NULL, (LPVOID *)&endpointVolume);
      defaultDevice->Release();
      defaultDevice = NULL;

      // -------------------------
      float currentVolume = 0;
      unsigned int icurrentVolume = 0;
      endpointVolume->GetMasterVolumeLevel(&currentVolume);

      hr = endpointVolume->GetMasterVolumeLevelScalar(&currentVolume);
      hr = endpointVolume->SetMasterVolumeLevelScalar(static_cast<float>(newVolume), NULL);

      endpointVolume->Release();

      CoUninitialize();
}

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Do you have any idea how to that ? even if it possible to use HKEY (regedit) or if i can control volume for specific process ?

Thanks