I'm slowly learning Windows 10 with my new little desktop. And I've discovered some "anomalies".

FIRST STRANGE THING: THE BACKGROUND.

Yesterday I changed the background (not a personal photo but one of the default backgrounds of Win 10).

When I turned on my small laptop/tablet in my bed (under Win 8.1, the PC, not the bed), some hours later, surprise, wow, oops, WTF: the background was changed!
The same background I'd installed on my desktop!

No problem, I like that image but I don't understand. Perhaps (sure, no doubt) Windows is smarter than I am...

  Actually I was very surprised when an 8.1 computer stop asking me to install win 10 and just told me it was installing win 10.  Actually they put mind reading into the computers so it made a change for you, ho (joking)
Get a cat and if something strange happens you can just blame it on the cat like I do.
Carl2

Sound like "wallpaper syncing" is enabled on both your computers, it's clever this windows thing.

Personally I think Carl2 is correct, it's probably the cat   

But if it isn't the cat and you want windows to stop doing it, you could disable it.

Yes I had that happen to me too - certainly surprised me.

Hi Carl2, and lol. Windows 10 is an optional update and must be unchecked. If not, the update starts.

  It may have gotten unchecked, maybe the cat did that although I doubt it, got done not that it matters now.  So that is what syncing does, haven't had it happen yet. 
Carl2

Thanks for your explanation Data. Another strange fact soon...

SECOND STRANGE THING: THE WIFI.

Not a problem, just a mystery. When we have to enable a wifi connection, it's always not easy to enter the WPA code, very complicated (usually I use a flash drive with a text file for that)

With Windows 10, no need to have the code, but I don't understand why. Because after a fresh installation on my brand new PC, internet was directly on! You see, not a problem!

I think that your WiFi thing is also related, GT. It's probably a part of the settings sync. The syncing of settings between laptop and main computer is all well and good for the most part, but it CAN be a problem, if it syncs the wrong way. had that happen last semester to files in my OneDrive folder, which I was using for school, and it wiped out an English essay and a project that I was working on for my Graphics Communications class. The GRC project was no problem, as I had a backup of that on a thumb drive, but the English paper had to be completely re-written. It turned out to be a royal pain in the bum.

Thank you for your answer Dave.

And sorry about your painful "incident".