Back in the late 90s when the yoyo boom hit I used to place the string behind my second knuckle on my middle finger. Ever since I started unresponsive, back in December, I started placing the string behind my first knuckle on my middle finger. I feel like I have more control and cleaner throws with today’s modern wide gap throws.
I also place the slipknot on my finger so the side with 2 strings faces my index finger, which is unlike most people from what I hear. That’s how I’ve always played and it’s the most comfortable for me. There’s not really a right or wrong, whatever is most comfortable for you.