My 20 lb Havanese likes to bully smaller dogs.?

I have a 1 1/2 year old Havanese who is lovable and very playful, never aggressive. But he is very rough with dogs smaller than him. He plays with large dogs (boxers & labs), and small dogs like Yorkies and other Havanese. He is very rough when he plays and larger dogs can handle how he plays and they don't bully or push him around, they are very gentle. He is not and likes to run-over and bite smaller dogs as if he is playing with a rag doll.
I scold him when he is being too rough and I make him submit and calm down, but when he gets up he is at it again. He is just playing, but a little too rough and now my friends don't want to bring their dogs around because he is always throwing them to the ground, biting them too hard and trying to hump them, especially the male dog (Yorkie). I know that sometimes two male dogs who are not neutered will hump for dominance, but my dog does it a little too much even after the dog has submitted and ends-up scaring the smaller male dog (Yorkie).
I don't know what to do. I have socialized him very well since he was 8 weeks, but I don't know what to do about his bullying ways and why he does it because no other dog treats him like that (big or smaller).

I think he is used to playing rough with bigger dogs and thinks it is ok to do the same to smaller ( maybe thinking they can handle it) it could also be a dominance thing showing htem whose boss