I read @Olive Hill post about gander behavior months ago when our white Chinese boy, Snow, was starting to give us trouble. It really works! I did go through a very rough patch with Snow, but now he is very respectful of me. All it took was a few pinnings and 1 chase around the yard and he not only acknowledges that I am top goose, he will discipline the other geese when they get out of line too. I have a young 12 week old African goose who is a terror and she is constantly trying to attack, when she came after me I was ready to grab and pin, but Snow got to her first! I am so proud of my boy, it was worth all the time spend teaching him his place and some manners. Snow is now 23 weeks old and a very different gander from a few months ago.
Now I have to teach my husband and sons the same techniques that allowed me to safely handle Snow, because Snow will still threaten them.
I can also attest that @RURU advice about pinching their bill when they bite works. Snow's hatch mate, Jasmine, is a lovely goose who still loves climbing in my lap for snuggles. Everyone has said geese are not tactile creatures, but for some reason Jasmine will climb in my lap and put her head under my arms. She does this voluntarily. However, she did start nipping at me and left bruises. So I started pinching her mouth shut and not letting go till she stopped struggling, along with telling her no biting. She is much better now, she will still occasionally nip me, and even gentle nips get the same correction. If she persists in nipping I put her off my lap, don't let her get back on, and give the other geese some chest scratches. Jasmine gets so upset that she hangs her head, give me pitiful hinks, but she does behave herself for a long time afterward. They are intelligent, but they do constantly push to see what they can get away with. Jasmine knows not to bite, and she has never threatened anyone or acted aggressive in any other way, but she is always testing to see if I will let her get away with it this time. On the other hand, Jasmine like Snow will discipline the other geese when they get out of line. Sometimes it makes me feel bad for the offending goose, getting disciplined by myself, Snow and Jasmine, but I don't feel bad enough that I let it slid. Give a goose an inch and they will take a mile.