What Am I Riddles

Question: I attach to your hip and I sing all day.
All I want to do is play.

Question: What gets easier to pick up the larger it gets?

Question: Living I do not exist. Dead I am an inspiration. You always doubt me. But never reject me. I am what is given from old to young. Without me people would not learn mistakes. What am I?

Question: Not only a seat, it’s also a head - what is it?

Question: I always murmur but never talk, i always run but never walk, and I have a bed but I don't sleep. What am I?