My comparator doesn’t have that yellow test side, and it has smaller ranges. Even then I find that if I use my thumbs or fingers to cover neighboring colors I can focus in better on the hue. Having so many extra colors around in your pictures really confuses my eyes. I think with that test kit I’d use some card stock to cover the yellow side and to limit the view on the pH side to two blocks and slide the cover up or down as necessary to determine where you are. I also find that using a pale beige background helps (conveniently the color of my walls). Maybe reducing visual distraction would help.