How to turn on automatic logon in Windows - Windows 10

Summary

This article describes how to configure Windows to automate the logon process by storing your password and other pertinent information in the registry database. By using this feature, other users can start your computer and use the account that you establish to automatically log on. 

Important The autologon feature is provided as a convenience. However, this feature may be a security risk. If you set a computer for autologon, anyone who can physically obtain access to the computer can gain access to all the computer's contents, including any networks it is connected to. Additionally, when autologon is turned on, the password is stored in the registry in plain text. The specific registry key that stores this value can be remotely read by the Authenticated Users group. This setting is recommended only for cases in which the computer is physically secured and steps have been taken to make sure that untrusted users cannot remotely access the registry.

Use Registry Editor to turn on automatic logon

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756 How to back up and restore the registry in Windows

To use Registry Editor to turn on automatic logon, follow these steps:

1. Click Start, and then click Run.
2. In the Open box, type Regedt32.exe, and then press Enter.
3. Locate the following subkey in the registry:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
4. Double-click the DefaultUserName entry, type your user name, and then click OK.
5. Double-click the DefaultPassword entry, type your password, and then click OK.
   
   Note If the DefaultPassword value does not exist, it must be added. To add the value, follow these steps:
   
   
   1. On the Edit menu, click New, and then point to String Value.
   2. Type DefaultPassword, and then press Enter.
   3. Double-click DefaultPassword.
   4. In the Edit String dialog, type your password and then click OK.
   Note If no DefaultPassword string is specified, Windows automatically changes the value of theAutoAdminLogon key from 1 (true) to 0 (false), disabling the AutoAdminLogon feature.
   
6. On the Edit menu, click New, and then point to String Value.
7. Type AutoAdminLogon, and then press Enter.
8. Double-click AutoAdminLogon.
9. In the Edit String dialog box, type 1 and then click OK.
10. Exit Registry Editor.
11. Click Start, click Shutdown, and then type a reason in the Comment text box.
12. Click OK to turn off your computer.
13. Restart your computer. You can now log on automatically

Source: https://support.microsoft.com/en-us/kb/324737