How should I deal with my family members always asking me for money?

( F 18 ). I have recently gotten my first job at a fast food restaurant and everyone in my family would ask me for money. My dad would find something everytime we would go shopping or find something on ebay and ask me to buy it for him or he would ask me money for gas or for a bill. My younger brother has a job as well and he has an expensive car and is very picky about food so he would ask me to buy food for him. My dad has a saving account and I would transfer money there everytime I would get paid and my older brother would take money from that account and he would return the money weeks later but what pisses me off the most is that my older brother has a job and gets paid a lot more than me like $2.500 per month and I don’t get why he touches my money and he takes my money without my permission. I know that you’re supposed to help your family and everything but I just get annoyed because they don’t spend their money wisely and they wouldn’t save any money and turn to me for help. What should I do?