My dog is out of control?

I'll start by saying he's a pug so I know that generally speaking they take longer to train. But he is quite out of control. He listens only when it suits him and he still defecates in the house. It's been months. I have tried treat training, being the nice guy, being the tough guy, and they all seem to work for a time, and then it's like after a couple of days he forgets what he's learned. I know people say commit to one and stick to it which I have also done, but he still doesn't seem to get it. He also bites everything despite having plenty of hard toys and treats to chew on. He thinks biting peoples faces is playing and when he's in that mood it's almost impossible to control him. On top of this he constantly barks at my family's other dog and will listen to no one when we try to get him to stop. We're currently taking him to puppy school which is a real hit and miss situation with him, but I really don't know what else to do. Does anyone know why and how to fix these traits? Thanks.