How can I stop my dog from being so violent?

my 1 year 1/2 old puppy bites anyone who comes into the house_when I tkae him on walk he trys to attacks little kids and seniors_ he is the most loveing dog when its just me and my close family but other wise he will make you bleed_how can I help him not be so violent

if its being mean and really agressive to people then you need to look back and think of the previous owner and what they may have done to the dog. if its always been yours and your gone in the day time and someones watching your dog then think about what they might be doing to your dog...I had a pitbull and it used to be really nice and I used to let the neighbors babysit it then I noticed a change in its aditude and it had bad marks like nails from a board were stuck in its skin the neighbor told me he broke through the fence and got scratched up ...then 1 day I came home from school early and heard a lou noise/scream and I snuck into my side yard and looked through the fence to witness my dog as a bate dog in a dog fight ring...my dog had to be put down from those wounds...if I were you then put up some hidden cameras in your house or your yard just in case