I don't know if this advice will help any!
I find my mares, don't keep any geldings, that act like this are normally wanting to be boss mare but they are not! Right now I have 3 mares,, the #2 in line mare chases the dogs and the cats and would bite and kick them given a chance.
When I first got her she kicked my daughter and she swings her hind end at me when she is feeding. She was nippy when I got her. Just as an FYI she is most dominant when food is involved but was malnourished when I got her.
However, I have NO tolerance for horses hurting me and now she knows this she never nips or tries to kick BUT does it to the dogs/cats, because they tolerate it or submit to her!! I think she just wants to boss someone around!! One of my dogs stands her ground and growls at the horse and she leaves that dog alone!
I think much of this is normal behaviour, you just have to let them know it is NOT acceptable to you, like another horse would.