I would suggest keeping your dog on a long line whilst out, so he can run around and play, but you still have ultimate control if he ignores you. Unfortunately at the moment he is learning, ignoring your call is fine, and running up to every other dog and person is also fine, which it isn't, before long he will get some bad reactions from other dogs, who will tell him off or worse fro jumping on them.
As has already been said he is very young, and at the moment untrained, he also has not had time to build a relationship with you, so would rather be with you than other dogs/people.