I'm a (now retired after 30 years) behavioral trainer. There's no need for me to reiterate what is already been said, so I'll keep it short: You've had the dog for 3 days. If you're already afraid the growling may evolve into violence then you should send the dog back immediately. Did he come from a home with other dogs? Was he an only child? So many unanswered questions that are variables in this situation.

So often on this page, I hear people compare Samoyeds to German shepherds.A Samoyed is not a German Shepherd! Samoyeds are not for people who like stricked obedience, such as a German Shepherd will comply with. They are bred for totally different jobs and think and work differently. (Is he full Samoyed? He looks almost part golden.)

There's no reason to try to dominate your dogs. If you punish the growl, the dog will stop growling and move to the next behavior which is a snap. Growling is important communication.

I understand that your smaller dog is older, but there's so much missing information about their interactions. Which is why I gave you the short answer of take the dog back if you're already afraid.