Do you think it’s the young peoples fault why COVID-19 cases are rising again? ?

Not entirely, but it's a contributing factor.  There are all kinds of people acting irresponsibly.  Some people understand why we need to keep our distance and some people don't.  Maybe more young people than old don't get it, but that's not all that surprising.

No. It's because the virus is mutating! You hear on the news there are now variants of the covid19 strain. Viruses often mutate 

It's the fault of politicians relaxing the guidelines too soon and of people who don't floow the guidelines young or old.

Mostly but not solely.

They are quite low where I live hun.