That is very broad. Might you narrow it a bit? Ask a different question. What are the responsibilities of youth in education/religion/positions/society? Each one provides a different answer. Also put into consideration, where are they? Each country, or even in different cities, expects different levels of responsibilities.
They are expected to achieve a good education, a bachlors to most, and from that education to achieve a good job. They are to make money for themselves that they might have what society calls "a good life". After they do this for a while, the students get married. They share their life with someone, enjoying the other persons company. Then they should be middle aged and thus do not qualify as youth.