Welcome to the forum!! What's your puppy's name? We would love to see some photos. Sounds like you're on the right track with your obedience work and getting signed up for class. It's just a matter of doing your homework (daily practice) and being consistent. The teenage months can be tough but it's worth it in the end

He will turn a corner and then you'll be looking at old puppy photos and wondering where that sweet, sassy baby went.
I have loved this forum, it's taught me so much about dogs in general and goldens in particular. The nice thing is that you can't come up with an issue that hasn't already been discussed here, lots of answers.
When you work on walking on the leash, do you carry a baggie full of his kibble, maybe with some treats mixed in? Measure out his next meal into a baggie and take that with you everytime he's on the leash and reward him with a bite every step or two. Slowly begin weaning him off. When he gets that you can begin working on teaching him to "wait" (pause) while walking and give you his attention. That is a good thing to teach when he starts getting really excitable and wound up. Good luck!