When you yell at your children, it's not you, parent, who's yelling, it's you individual.
You with all your backpack full of the education you received and the feelings and reactions of all the crises of your past. When my son laughs if I tell him off, the person who gives in to anger is the girl who wasn't welcomed when she felt strong emotions, who was teased by her peers, who was deprived of love for the mistakes she made.
When your child is disregulated, your answer is not just about the current crisis, but about all the crises that are already in your backpack. Your anger feeds not only on the destructive feelings of this very moment, but on all the destructive feelings of all the crises you have gone through in the past.
Yelling at your kids is not an answer to your present, it's an answer to your past. Start there if you wan to heal it.