I'm a high-school student in Michigan who works for a nonprofit which provides education for minors. Since the beginning, around ten years ago, the main two positions of nearly everyone at the nonprofit has been Lead and Assistant instructor. There is a large gap in pay and responsibility between these two positions.
Recently, the administration has gone through major changes, and the new manager (the only person who works in administration), has been continually and knowingly giving me the responsibilities that are supposed to be for Leads.
When the manager first started doing this, they said that it was because of the administrative changes, and that they were extremely busy, and that responsibilities were only temporary. However, its been a couple months, and its now clear that these responsibilities are not temporary. Since in the past, I have been payed less than other people doing the same job, this feels like the company is exploiting my age in order to pay me less.
If I were paid what other people in the same position as me were payed, my salary would be roughly 50% higher. I understand that it may not be an option to receive this salary, so is there a way I could make it clear to my manager that I'm not going to continue to do work for far less than normal pay, without sounding disrespectful or unappreciative?