sounds like spotlight which rotates nice pictures on the lock screen.

Did you download the pictures or did they just appear automagically?

sounds like spot light then

1. type "personalize" in the ask anything bar

--The first thing to come up should be "change the picture on your lock screen"

2. click on "change the picture on your lock screen"

-- once the screen comes up you should see the word "Preview" and a picture under it and then under that the word "background"

3. click on the box under the word "background" and it will give you 3 options. Click on the one that says "Windows Spotlight"




That should fix you right up.

There is:

Settings icon - "Lock screen"

The word "Preview"

Beautiful picture (with the current time & date)

The word "Background"

Drop down box with "Windows spotlight" in it

**********Below that are greyed-out icons for apps "to show detailed status"

little further down the screen is there a little slider below "show lock screen background picture on the sign-in screen"? If so then make sure that's on.

So where does the old time Beach cave picture come from? Is it part of the "Preview" pics rotation, meaning that the new beautiful pics will eventually start up again?

All this time it was the old Cave-on-the-beach one!1