Backseat driver is a term commonly used to refer to someone who offers unwanted or unnecessary advice while someone else is driving. A few synonyms for backseat driver are nag, micromanager, critic, armchair quarterback, and know-it-all. A nag is someone who constantly pesters another person with suggestions or complaints. A micromanager is someone who obsesses over small details and prefers to have control over all aspects of a situation. A critic is someone who offers opinions and evaluates actions, often with a negative tone. An armchair quarterback is a person who offers unsolicited advice to professional athletes or coaches. Finally, a know-it-all is someone who falsely believes they have expertise or knowledge on a subject.