SFTP chroot jails

Thats was helpful
but the question for me is:
sftp is good because of encryption, but
with my sftp client i could see - not write - root and so on
with ftp the client does only see his home area
with sftp he can go up to root /
how can i adjust the behaviour same like ftp?
ok i see there is a vsftp configuration file. but help would be appreciated
Best regards Markus