The problem you are probably receiving is that while the display may be physically very large the resolution is only "Full HD" which is 1920x1080 pixels. In order for Scale 3 or larger to work on the powder toy you would need a display with about 1896x1330 resolution, as you'll notice the second number of your monitor (vertical size) is too small for anything bigger than scale:2 so if you put in "scale:3" it will default to scale:1 to fit it on screen.
So in the end scale:2 is actually the perfect size for your monitor
I think it would be a good idea to add a Scale:3 mode, as a few very large monitors (~30") are indeed over 1330 pixels tall. Scale:4, however won't be needed for quite a while.