When writing gabc code, is it possible to have special characters (such as the R/ or V/) appear in another color, such as red? I am able to get the color to change but instead of the special character appearing in red, the code for the special character appears in red before the rest of the text. Is there a fix for this? Thanks!

Are you doing this in the browser? I managed to get this code to work for red V/ and R/ symbols there:

%%
(c3) () <v>\definecolor{Black}{rgb}{0,0,0}\definecolor{Red}{rgb}{0.9,0.3,0.3}</v><v>\color{Red}</v><v>\Vbar</v>.<v>\color{Black}</v>() Di(h)gn<v>\'</v>{a}(h)re(h) me(h) lau(h)d<v>\'{a}</v>(h)re(h) te,(h) Vir(h)go(h) sac(h)r<v>\'{a}</v>(h)ta.(f.) (::Z) <v>\definecolor{Black}{rgb}{0,0,0}\definecolor{Red}{rgb}{0.9,0.3,0.3}</v><v>\color{Red}</v><v>\Rbar</v>.<v>\color{Black}</v>() () Da(h) mi(h)hi(h) vir(h)t<v>\'{u}</v>(h)tem(h) con(h)tra(h) hos(h)tes(h) tu(h)os.(f.) (::)

It seems to me that the colours must be redefined each time you want them in the browser app, which is annoying. If you need to do a larger project it might be worth installing gregorio + Latex on your system, where it will be easier to define changes like this. You could define all V/s to be red for instance.

I just ran a test here, and an apostrophe worked fine. Check that the apostrophe in your GABC file is a typewriter-style (vertical) apostrophe ('), not a left- or right-leaning curly apostrophe, also called the "single quotation mark" (‘ ’). Some users have their computers set up to automatically change the typewriter apostrophe to the left/right style.