Hello i have RB912 and i have 3 user i want to see password of another user does there is a way to know password of another user

no, absolutely no. Passwords are encrypted in MD5. if you have an old version you could exploit the backdoors to trace the passwords or you could downgrade to 6.42

viewtopic.php?t=133533

if i had old version how can i get password?

Do u mean winbox u/p?
Use radius.

if i had old version how can i get password?

Depends on old version, this can be used for ROS versions 6.13 - 6.45

how to use the tool?

no i mean system user

how to use the tool?

There are examples on page (steps Decrypt->Unpack->Extract Users), it's Python script which extracts data from ROS backup.