I have had a few customers come in telling me that Windows 10 installed itself, and no disrespect to the customers, I took what they said with a grain of salt. However, the latest customer who rang and asked for my advice was someone I know reasonably well, and have great respect for his powers of observation, recall and analysis, so I did a bit of research.
It looks like Microsoft have started making some changes in order to get Windows 10 more widely installed, in particular with windows 7 customers. According to this article by the Guardian, the Windows 10 priority has been changed from “Optional” to “Recommended”, only “Critical” is a higher priority. For most people this will not make a difference. However, in the update settings it is possible top specify that all recommended updates are downloaded and updated automatically. Microsoft deny that the update will start without notification, but opinion out there seems to suggest that it will.
In my latest case, the user is not able to find pictures and documents in the applications he normally uses (Wordperfect and Lightbox). Hopefully they are still there, and the system did not do a full reset while updating!