I have the training collar and my dog will just drag me around like it’s not even on him . Best ways to work on fixing this ?

Hello I have a 10-week-old GSP. Im currently working through the course and trying to teach “come & go with me,” but whenever I try to get him moving, he’ll either jump up and bite at me, grab and attack the leash, constantly jumping until he gets a hold of it, or plop down on the ground and refuse to move. I’m feeling a little stuck and not sure what I’m doing wrong. Has anyone else dealt with this or have any tips that helped? I’d really appreciate any advice!