My mom never stops yelling? Help?

My whole life my mom has always yelled at me and my little brothers. I'm 13 and my little brothers are 10 and 4 and my mom can't just like talk to us in a normal voice she always has to yell espescially when shes really mad. And she yells at us for really stupid things sometimes like spilling water which is so easy to clean or if we didn't hear her or something. Everyone in my family has tried to tell her she needs to stop yelling, but she thinks she knows absolutely knows everything so she won't listen. Last night me her and my 4 yo brother were driving home and she was yelling at him because he was upset because he dropped his cars on the floor and couldn't reach them (hes very sensetive about his cars) and I was fed up so I told her to stop the car I was gonna walk home and so we got in to a big fight about it and she kept telling me about how im not a parent i dont know what im talking about and im the kid and shes the adult so that means eveything i say is wrong and shes right and that i need to stop telling her what she needs to do and if she doesnt yell we wont listen which isnt true. I babysit my 4 yo brother and he listens to me and i never have to yell or spank him and I cant take her yelling anymore it makes me not even want to be around her anymore and were homeless right now im at the library using the computer and no one wants to let us live with them because they cant stand her yelling all day for no reason. So what should I do I really need some help please