The Secret of My Succe$s (1987) on Netflix

Brantley Foster, a well-educated kid from Kansas, has always dreamed of making it big in New York. On his first work day in New York, he is fired in a hostile take-over and learns that jobs - and girls - are hard to get. When Brantley visits his distant uncle, Howard Prescott, who runs a multi-million-dollar company, he is given a job in the company's mail room. Then Brantley meets Christy Wills, who happens to be one of the top executives. Brantley sees how poorly the company is being run and decides to create a position under the name Carlton Whitfield, to influence and improve the company's operations. Soon things get unexpectedly out of hand, not in the least because of his aunt, his girl and leading a double life.