If the other person says "you don't understand the world of young people", you can reply in the following ways:

1. I may not fully understand the world of young people, but I try my best to understand and respect it.

I may not have a young mind like you, but I have a heart that is willing to learn and accept.

I know the world of young people is constantly changing, but I will try to keep up with the times.

If you have any suggestions or opinions, I am willing to listen and try to understand.

I will try my best to understand the world of young people, because I think this is the key to building a bridge of mutual understanding and respect.

In any case, show your respect and sincerity, and your interest and concern for what the other party says.