While it is not exactly good solution you could try zooming in with crtl +.

I have quick look at the practise problems and did not have any trouble telling the difference between the division sign and +. In addition, my computer has the same vertical resolution (1920*1080).

It may be a good idea for you mess round with the display settings on your computer.

I've had the same problem. Accidentally hitting plus. But I have a better solution than zooming in. I made a post advocating for the Desmos calculator; at least for Digital SAT Math prep we should have access to Desmos because that is what is available to Bluebook test takers. We have access to Desmos on every question on the new Digital SAT Math.