How do I make my parents stop fighting?

The simple answer is that you really can't. What you can do is realise that it's not your fault they fight. Maybe you could try talking with them and letting them know how much it affects you.

Understand that their fights are not your fights. You are not entitled to always resolve their conflicts. Parents are grown up individuals who can very well handle themselves. Don't try to pitch in every time hoping you could help, 'cause it will hardly do so. You might succeed to stop the fight but they're bound to explore again. Also, taking sides does way more damange than you might think, so it's best to just stay out. Care for yourself, that's the most important thing!

You can’t make them stop fighting the best thing you can do is just let it run it’s course.