I Have A Mirena IUD, For 4 Years So Far.

I have a Mirena IUD, for 4 years so far. My boyfriend is getting scratched/poked when we have sex. I looked online to see if cutting the strings would fix this. But I see mixed reviews that cutting the strings would make this worse unless cut super short to the cervix, or the complete opposite. That it means the strings aren't long enough. What is the best solution for this?