I try talking to my parents about something important but whenever I do they ignore me and completely change the subject what should I do?

Sometimes when I want to tell someone something important and they don't listen or ignore me, I try to write it to them. I write everything what's in my mind. I put emotions in it, and everything what I'm thinking of at the moment. Or I try to come to them and just say that I'm sad that they never listen to me, but I need it because I have a lot of things to tell them and I need them listen to. These things are very hard to do, but once you find confidence, you need to risk everything