I had the same problem. I started training mine on a pad in the kitchen. Once she was trained there, I let her into the room next door (the living room) while keeping all of the other rooms blocked off with gates. She did have accidents so you have to watch them like a hawk. I left her leash on her while she was running around so if they sniff around, clap to catch their attention, and drag them to the 1 pad in the kitchen. It took about a week before she got a hang of it.
Once she was good in the living room and knew to run back I would let her into the next room.
Problem is that I'm trying to outside train her now and took away her pad in the kitchen but she still runs and pees where it used to be.

I'm probably confusing the poor puppy but I'll keep trying!