I do not know what the previous reviewer was doing wrong or if they even know how to change out the jewelry for a nipple piercing, however I had no trouble putting them in. The keys look amazing and are so comfortable. They lined up perfectly! Both sides of the keys screw and unscrew so you only really need to unscrew one side. I choose the top of the key. It did not loosen or anything and I have had them in over a week. I feel like a super hero! Definitely acquire these!