The working population is getting older, the population in general is becoming more myopic. Why ever did MYOB remove font sizing from their program years ago. It would help reduce typos. Most other types of software suites have this facility.
Changing the windows screen resolution does not fix the problem.
Ever heard of the science of Ergonomics?
A resize font option would deliver an ergonomic productivity improvement to a large cohort of your customers.
Good Ergonomics makes good economic sense.