Hi Fred. I will humor you :-)
Let me first say that previosly I would have the thumbs of my fold of images showing in nthe thumbs pane. By clicking on one, it's size, or it's size and any other scaled size would light up in blue in the Prints box that opened. This was good for two reasons. One it meant it was easy to find the size I wanted (say 10x8 or 20x16) as they were all easily seen, and two, it confirmed to me that I had croppe the image correctly. This was importatnt as if for instance I had cropped an image 9.25x12 and put it in the 10x8 folder, when I clicked on it, it would not highlight 10x8 and i would know there was a size problem.
Now when I click on an thumb, no size shows in Blue.
That said looking at your instructions above
I select a 10x8 folder, it does mean something to me, it means those image should be a 10:8 scale.
So I click on 10x8 in the list of sizes as you have asked..... 10x8 template/s appear. Nothing in Blue
I select a thumbnail....A white tick on a black square appears top left on Thumnail.... No size appears in blue on Print list.
So following your list I click on 10x8 ......The picked thumbnail appears on my sheet as a 10x8. but i had to search for where 10x8 was listed, boring to do when an odd size is needed and there are lots of sizes in my list.
much easier with the old old system when the relevent sizes automatically appeared in blue.
You say click on the little Plus to add to the queue, but I dodn't have to do that as it added when i hit the size.
....and still, my Print size is not in blue, or boxed in yellow.