Young Buck in the office

I am not a young buck, but I do look the part. I have a somewhat young face, which makes me look a little younger. I feel young. I suppose at times I act young. But when I am in a position of authority over a person in the workplace I have have older people resistant to hearing what I have to say. This was especially troublesome in NY where the man coming in took over responsibilities I was directly trained to do and he had no clue how to start. His solution was to let me keep doing it and then he suffered when I left the company, because he never swallowed his ego and let me show him the deal. I find this happens more than I would like to know. I sense it.