To change any CLI passwords you have to login as user root and then type the passwd command followed by the actual username for which the password should be changed.
[root@server ~]# passwd ospadmin
Changing password for user ospadmin.
New UNIX password:
Retype new UNIX password:
passwd: all authentication tokens updated successfully.
[root@server ~]#
Note: The CLI passwords don’t have match the UI passwords.