Is there a way to edit the writing that is already on a YouTube video? Just the color of it.
If you are talking about annotations then it can be edited by clicking edit info.
hard-coded text cannot be edited, for that you will have to go to edit video and
apply effects on video, which will affect entire video.
If you have added text through youtube by add text option, then you can try to edit from the same option if available, but I am not sure.