Google (Senior) Software Engineer interview questions

Why did you leave your past position at so-and- so company? Explain adwords to a 7 year old who doesn't know what it is. Why this position (relate a lot of your past experiences to the job description and be REALLY thorough. my interviewer was literally like "thats it?" and i listed off like 10 qualities that would be perfect for this job.) what would you bring to this position? what is your favorite google product and what would you change about it

Initially was contacted by HR on email and phone call. I had 3 Video conference interviews at Google. All of the interviews were Technical rounds. I was asked for Salesforce trigger as well as Apex code.