Hi Greg,
Welcome to the forum.
What exactly can't you see?
There isn't a way to increase the size; yours looks about the same size as on my screen and I have no problems - the text etc. is normal size, see attached.
However I do see a problem with the target image showing on your screen shot, it's too small.
Look at my screen shot and you can see the target image is much more magnified.
The resolution of the target image is too small, that is why it's difficult to see in addition to it being a problem for PP to select the patches.
Terry

Hi

Are you using the Canon Software to scan your image, Have you tried using Vuescan.

I find Vuescan better for both Canon and Epson scanners over the makers own software.

Paul