change password for cisco switch , router, pix

What kind of password are you trying ot change?  Specifically a local username and password, the enable password, the exex password, etc.  Do you curently have access to the device?

Here are the password recovery procedures for almost every Cisco device. Handy to keep bookmarked..
http://www.cisco.com/warp/public/474/index.shtml

Changing telnet password, user passwords, and other passwords depend on the product model and whch passwords you're needing to change

hi
thanks for all reply
sorry my question is not clear
my question is how i can change password (i mean password for entering the device and for enable and for telnet ) for each router and pix and switch
>>>>Do you curently have access to the device
yes i can enter to the device but i want to change the old password

thanks

hi
thanks for your reply
for switch  
Sw1(config)#enable secret <new_secret_password>

Sw1(config)#enable password <new_enable_password>

Sw1(config)#line vty 0 15
Sw1(config-line)#password <new_vty_password>
Sw1(config-line)#login

Sw1(config-line)#line con 0
Sw1(config-line)#password <new_console_password>
----------------------------------------------------------------
for router
Router(config)# enable secret <new_secret_password>

Router(config)#enable secret <new_secret_password>

Router(config)#line vty 0 4
Router(config-line)#password <new_vty_password>
Router(config-line)#login

Router(config-line)#line con 0
Router(config-line)#password <new_console_password>
----------------------------------------------------------------------------
for PIX
PIX(config-line)#line con 0
PIX(config-line)#password <new_console_password>

PIX# enable password <new_enable_password>

PIX#password <new_telnet_password>
------------------------------------------------------------------------------
is the above command  true or not

thanks

hi
thanks for your reply
>>>You cannot apply a password directly to the serial console port, but you can set the console port to use AAA local username/password. Pix calls the console port "serial" port
  aaa authentication serial LOCAL

please can you explain more about this

thanks

hi
thanks Irmoore