#cs
You will need two .au3 scripts with the code below with the end keys changed. One for admin (or desired account) and another for default account (or desired account).
#ce

#cs
Enables AutoLogon
#ce
RegWrite ("HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon", "AutoAdminLogon", "REG_SZ", "1")
#cs
Set USERNAME
#ce
RegWrite ("HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon", "ashley", "REG_SZ", "USERNAME")
#cs
Set PASSWORD
#ce
RegWrite ("HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon", "Upd0wn", "REG_SZ", "PASSWORD")
#cs
Set DOMAIN
#ce
RegWrite ("HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon", "ASHLEY", "REG_SZ", "DOMAIN")


#CS 
The code below goes into new .au3 script.
The passwords are stored in the registry as clear text so you will want to delete that key.


Disables AutoLogon
#ce
RegWrite ("HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon", "AutoAdminLogon", "REG_SZ", "0")
#cs
Deletes Password Key
#ce
RegDelete("HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon", "Upd0wn")