Amazons are stubborn animals and they will continue testing your authority several times a day for several months, until they realize that you are not going to give in. I believe all Amazons should be stick trained as well as hand tamed. A mature Amazon during the breeding season, especially if a bird of the opposite sex is kept near him, can be quite hard to handle. During this time, having him stick trained will save you from several bloody bites on your arm when you transfer him in and out of his cage. I also believe that Amazons should not be kept on a person's shoulder.
Accidents occur in seconds.
A large parrot can injure an eye, pierce an eardrum or disfigure a face. I tell most owners to teach their birds to remain on their wrist and not to let the bird wander up to their shoulders. A parrot will always attempt to scramble to the highest point. That's encouragement for him to dominate over you. He is at eye level on your shoulder and feels more in charge.