http://www.addictivetips.com/windows-tips/disable-login-screen-in-windows-10/ has a note to uncheck a box but in your case you want it checked.
I just recently bought a PC that came with Windows 10. After all the initial set up and creating accounts for my family, I turned it off. When I turned it back on, it immediately went to the "Owner" account without requesting who would be using the computer. Is there any way to set up the Power on feature to allow us to log into our own accounts? Thank You