Even dragging the mouse across all clips at once to select them all will not easily move the clips in the same track since the others will move to the track below where they were at the same time. Sadly I looked up online and even tested it out on Premiere Pro myself and could not find a way. If I ever do find a way, I will be sure to share it with you. So for now, you may need to do them individually to move them to the same track. I would suggest to move all the clips next time to the Project section on the bottom left side and then drag all of them at once into the same timeline this way, its very possible this way 🙂 Hope it helps.