Hey, Anbuja's probably busy so I'll show you how to do it:
In that image, I have circled out 7 colors. Those are the palette of the textbox, which means if you change 147B (or either one of the 7 colors) to something else, you'll be changing the color of the textbox. But since you only want to edit the color of the text, you want to focus on the other 9 colors. You notice there are three exceptionally bright colors? They are 3C04, 6406 and 4665. They are also the few main colors that you use. For example, I want a female to use red text, so I use the script command of 3C04, Red - [red_fr] but in your case, let's say you want a female to speak with purple text. So you change the RGB of the red (assuming that you want to edit red to suit your preferred color) to purple:
Once you are done with that, just save it. You wouldn't notice any change in the img of the textbox. Don't worry, that just proves that you haven't edited the color of the textbox

now, let's make a character on a-map!
Next, I wanna edit his script:
In case you don't know, \c\h01\h04 is the old hex command for red. You can copy that script if you want.
Now, let's test it out
voila! we're done. If you need anymore help, feel free to ask me or Anbuja!