I don't know who assigned "Gill Sans" as the default font. You can not tell the difference between the letter 'l' the capital letter 'I' and the number '1'. Absolutely maddening, How do I change the default font so that each new Notebook will open in my choice of font. BTW, does anyone have an opinion as to which font is most legible between small and upper case and different from numbers, meaning the number 1 is not confused with a small letter 'l' or a capital "I". Thanks for the help.
I raised this issue when the default style sheets changed radically in Mathematica 9.
In that version, there was an option to keep the older default style sheet for old notebooks, and you could deliberately select the older style sheet for new documents.
You can edit the default stylesheet -- it's just a notebook, after all. It is tedious, but you can change the fonts to whatever you want. The problem is that this stylesheet will revert with each update. If you send a notebook to another person, they will see it with their default stylesheet.
The best solution I came up with, which I use when it matters to me, is to make a custom stylesheet with a better choice of fonts, and use this as the private stylesheet for the notebooks in question. If you just point to a private stylesheet, any notebooks you send or can't link to will have a missing stylesheet error.
If you go this route, DO NOT edit the styles for Input or Code. You will screw things up royally if you do so. There may be other similar styles that need this type of care.
The better solution would be for Wolfram Research to change their default stylesheets to something a bit more useful or aesthetically pleasing. I prefer my body text to be seriffed, and for my Sans Serif fonts to distinguish between "I", "l", and "1" -- note that whatever this website uses fails in this regard.
I also prefer slashed zeros, ligatures and other typographic niceties, but this is not a word processor, after all.
At one time, seriffed fonts did not look good on a CRT. Those days are gone. Even non-Retina displays can show pretty much any type face well.
I hope that someone from Wolfram Reserch will respond on this thread.
using the pull down menu "Format" then > "Style" and then the nine commands for various style sheets, this is what I get. After the cmd# are three small "l" followed by three capital "I" followed by three number ones.
only cmd9 'input' can one begin to tell the difference, and even there the "l" and the number "1" are pretty damn similar. How can I permanently change this default font... to something that is readable?????
Which cell format? Input cells are Courier or Courier New and should not be changed.
Ten minutes later:
I went spelunking in the deep-down style sheets and found that Gill Sans is used
for Title, Subsection, etc.
Choose "Show Fonts" from the "Format" dropdown menu. Here are three characters using Lucida Grande:
i I 1