the age of the universe

hi there

I have checked out and watched loads of documentaries. What I don't get is, people say the universe is 13.7billons yrs old and in that time it has been expanding. So you would expect the stars to have formed and be older than the 13.7 billon yrs it has been around. But what I don't get is the sun has a 10billon yr life span and if that is right then when it first ignited as a star it would have been very close to the centre of the universe where the supposedly the big band happened. So surely scientists and cosmologists have got it wrong somewhere along the timeline. I am no expect but expect for the scientists to talk to each other!