I have a female, almost a year old, and we had a lot of issues with aggressive behavior too. What helped her is grabbing her muzzle firmly, holding it shut, while saying "no bite" over and over. We did it every time she bit anyone and it really made a difference. She still has an attitude about her, and if you give her an inch she'll take a mile, so we have to revert back to tactics like that if she gets too wild
