no "start teamviewer with windows"

I have a Win XP I have set up as a host to a Win 10 desktop.  I would like to access the host without having to log into it and looking for the password every time, and in fact do away with the monitor.  I see that there is supposed to be an option under Extras -> General of "start teamviewer with windows" but it does not appear on the Win XP (or Win 10).  How can I have TeamViewer run automatically at startup?