Biff is upset because his father no longer has any liking for him. This also makes him mad at Biff because he's jealous of his brother. Happy offers for Biff to come work with him so that he can make more money and make his father happy.
You should come live with me and work for me!
Why does dad hate me? I never did anything to him!
Biff finally takes his brothers advice and decides to stay in New York and try to get a job there. This will hopefully please his brother and make him proud.
It seems like your other jobs are not going to well you should stay.