In modern society, it seems like children and teenagers are growing up much faster. They act like grown men and women at a much younger age. It may be because of technology and social media. They see things at a young age that children in the past did not even get to see in their whole lifetime.
If I could change one thing about modern society, I would bring back the playful innocence and simplicity, that is getting rarer and rarer; in children, teenagers but also in adults.