to start off it would help to tell your parents how it makes you feel when they yell and talk to you in this manner. Ecclesiastes 3:7 says that there is a time to speak and a time to keep quiet. so discern a good time to talk with your parents and discuss wih them how you feel. also when you are feeling good take note what is causing these good feelings, is it the people, a certain meal, a tv show. whatever it is that tends to brighten your mood. take note. maybe keep a log or notebook that you can write these things down in. i hope all goes well with you.