According to the here article, when you use the Auto login feature in windows 7, the Taskbar will be reset to default settings and we will forget the settings you made.
Solution 1: Let’s type netplwiz in the search box and press Enter and tick the following marked:
Solution 2: apply the following registry entry
Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionWinlogon] “AutoAdminLogon”=”0”
paste these codes into a notepad and click File – Save As…
Give any name in the window that opens (edit the filename as you want) and save the extension as .reg and run