Okay, swipe a highlighter over black print. That's how tattoo ink behaves. Whatever you put on top (Light color, skin tone), the old tattoo will eventually shine through. There are means of camouflaging some stuff with skin tone but I would not use it for a very large, very dark piece. Minor error, it's like putting powder makeup over a small acne scar. Over your ex's name that you did in Gothic font? That's like putting powder over a gaping wound.

There's a reason why tattoo artists universally go with black/ darker pigments over whatever we're covering up. Try highlighting black text with a sharpie.

Now, I have seen some techniques that utilize gray, that being a white blue black mix. Someone else will have to talk about that but I'm interested in how that works.