Does compile to mobi always start with Chapter One?

I have a draft folder with 5 text files in it. When I compile to Kindle (.mobi), “Chapter One” always appears above the title no matter what I name the draft folder, or what compile settings I use. I notice that doesn’t happen with other compile formats like PDF and .epub. Is this just the way .mobi works?

I have not been able to figure out how to create a Chapter Two from any of the text files. How do you do that? I have made folders and put a text file inside but that doesn’t make any difference.

Thanks for help.