Goofy puppy isn’t as goofy as I thought

My cousin called and asked if I could come please help her with her 95 pounds and 11-month-old boxer English bulldog cross. I have been telling her since it was a puppy that she needed to teach it how to walk on a leash. She finally needed to take it somewhere and it jerked her down the steps. In her defense the dog weighs about the same amount as she does. I came over and worked with the dog for about 15 minutes about a month ago. The dogs need to go back to the vet so I went over to help her. I told her that I wanted to work with it in the backyard first for a few minutes before we left and ask her to video it. When I got to working with him I think he remembered everything I can tell him in the 15 minutes I worked with him last time. The goofy puppy isn’t quite as goofy as I thought he was. She just doesn’t know how to communicate with him. He is the pack leader when she is around.