Wiktionary
you're the doctor
phr. Indicates that the speaker defers to another person's authority
Wikipedia
You're the Doctor
You're the Doctor is a 1938 British comedy film directed by Roy Lockwood and starring Barry K. Barnes, Googie Withers and Norma Varden. A young woman pretends to be ill to avoid going on a cruise with her parents but this leads to a series of confusions.
It was made at Isleworth Studios.