Always show all icons and notifications on the taskbar, command line

This will show all icons for current user:

reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer" /v EnableAutoTray /t REG_DWORD /d 0 /f

This will hide all icons for current user:

reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer" /v EnableAutoTray /t REG_DWORD /d 1 /f

To restore default settings use:

reg delete "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer" /v EnableAutoTray /f

This will show all icons for all new users on local machine:

reg add "HKLM\Software\Microsoft\Windows\CurrentVersion\Explorer" /v EnableAutoTray /t REG_DWORD /d 0 /f

The recommended settings can be to delete settings in current user and take global setting from local machine:

reg delete "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer" /v EnableAutoTray /f
reg add "HKLM\Software\Microsoft\Windows\CurrentVersion\Explorer" /v EnableAutoTray /t REG_DWORD /d 0 /f