He thinks he knows all the answers, but he's often wrong.
know all the answers
Frequency:
65
%
Don't act like you know all the answers, no one does.
have the answers
Frequency:
60
%
She claims to have the answers to all of life's mysteries.
Idiomatic Expressions for have/know all the answers
Phrase: think you know all the answers
Meaning: to be overly confident in one's knowledge or abilities
Usage: Don't be so quick to think you know all the answers; there's always more to learn.