Vsftpd permission users

I have something I do not understand very well. My Ubuntu machine ямс is admin Убунту Вен I send administrator username and password mypassword have permissions to anything in the FTP server. How хан I принимает решение which user gets some kind of privilege??

In addition, I checked the file vsftpd.conf and the ftpusers file in the folder И Т.Д. Бут I found nothing related to permissions!