====== Add logon as a service right to an existing user ======

  Open 'Local Security Policy' app. You can type secpol.msc in Windows search.
  Then go to 'Local Policies' --> 'User Rights Assignment' --> 'Logon as a service':
  
{{:windows:pasted:20191002-162410.png}}
  
  Then click on 'Add User or Group' button:
  
{{:windows:pasted:20191002-162708.png}}