Pistacio

From the U.S. Usually a minor noise or a minor bathroom cleanliness issue

I rent out 3 rooms in my home. We all lead seperate lives and don't socialize. I get along with all 3 of them. They don't get along with each other at times. When one of them has a problem with someone, that person comes to me and says "I don't want to start any trouble but......" and wants me to fix their problem. Is it my responsibility to correct their problem or should they go to the person they are complaining about and solve it on their own ?