FWIW, selecting for display (I assume in Explorer, rather than in Paint?) has nothing to do with the selection that I am talking about in my edit message.
The selection I am talking about that causes the problem is after you have already opened the single image within Windows10 Paint, but before you click the resize button in the Home tab.
I don't know what problems (if any) that selecting multiple images would cause, prior to editing in Paint.
If you are choosing to resize outside of Paint, like in a right-click menu in Explorer, I have no idea what Windows10 does or what the results would be.
In case something is happening outside of Paint, don't use Explorer to view or load the pictures into Paint, just open Paint directly from your Start menu, and then use the steps listed at the end of this post.
Try noting down exactly what happens at each step you are performing, and post them up, and I'll see if I can figure out why it's not working. If you attach one of the original images to a post I can also try it here.
I've relisted below the same steps I previously gave, with step numbers at every point and some extra text for clarifications, so we can refer to the step numbers to find where the problem is happening.
1 Open Paint
2 Click File Tab
3 Click Open
4 Browse to JPG file you want to resize
5 Doubleclick it's name or thumbnail.
5A: After the image opens in Paint, do not click the image, or select anything, go straight to step 6
6 Click Home Tab
7 Click Resize button (in Image section of toolbar)
8 In Resize and Skew dialog, Click Pixels
9 Click in Horizontal textbox to right of that word
10 type in number of pixels wide you would like it to become
11 Make sure Maintain Aspect Ratio is checked
12 Click OK. At this point the background of Paint should be a shading color (probably darker at the top and lighter at the bottom), with the resized image in the upper left corner. If the background is solid white, it means one of the above steps did not happen correctly (most likely you selected some or all of the image before resizing, which you should not do).
13 Click File Tab
14 Click Save As (it will automatically save as the same file type (JPG, etc) if you don't need to select a different one).
15 Type a new filename for the resized image (so it doesn't destroy the original)
16 Click OK
17 All done.
, but assuming I ever get to building the middrive experiment part of the trike experiment, the cranks would be useful for building it so the power goes thru the pedal chain too. 
