This moral decadence comes from the United States (California), through Hollywood films that were previously limited to a part of the world and now with the internet is spread through social media.

what can be done to stop all the moral decadence in our society??

I believe that in theory it was necessary to heavily regulate the social networks that each country in the world, saying what these social media can and cannot do, as these social media use algorithms to manipulate the population. Or even create a firewall that restricts the internet.

However, nowadays it is increasingly easy for people to circumvent some state regulation, so the only option left is a quality school education, given that parents may not have time or do not want to take care of their children.

China seems to have found a way to put an end to moral decay by putting children to study for 15 hours a day, if they don't have free time, then they won't do anything wrong.

See below how is the day-to-day studying in China.