Solved by Valerio_Biscione in post #2 
              
              
                def concat_generators(*args):
      for gen in args:
          yield from gen
  params = concat_generators(model.img_encoder.fc.parameters(), model.qu_encoder.parameters() , model.fc1.parameters(),  model.fc2.parameters())

  optimizer = torch.optim.Adam(params, lr=learning_rate)

This may work. 
Yo…