My headphones won't stay plugged into the jack

I have a big problem with my Apple headphones, whenever I attempt to plug them into the headphone jack on my computer, they will not stay plugged in and they pop out. To get them to receive the audio, I have to hold them into the jack myself. I cleaned out the jack and attempted to use my sister's Apple headphones and they stayed plugged in, unlike mine. I also noticed that my sister's headphones' adapter is slightly longer than mine and has 3 white rings while mine has 2. Also, my headphones stay plugged into my iPhone 5. Do you guys know what the problem is and how to fix it?