try installing security updates only. try denying a specific update. try freezing you installation at a specific build number. try running a machine unattended for a month without it rebooting. and next time you update, check your settings. chances are good that something, somewhere, got silently reset to defaults.
the only option for personal windows 10 installations (i.e. non-enterprise) is to blacklist the windows update service. and with each update, you have to find a new way of blacklisting the service. the settings allow for some changes -- you can defer certain types of updates for up to one month -- but eventually microsoft _will_ push new updates to your device and they _will_, if needed, reboot your PC.