The headphones are too small. For "best results" nothing about the headphones should ever touch any part of your ear. The soft foam padding should surround your ear making a seal with your skull. The 'clamping force' may also be too tight if you get headaches. The desired clamping force should enough to keep everything in-place if you briskly turn your head side-to-side but loose enough to dislodge if you try to turn your head quickly.
Without a real metric/measurement I'd compare it to the 'normal' speed you turn your head to do a should-check-before-turning on a calm sunday drive, vs the 'Quickly twist and look if the monster is still chasing me' shoulder-check.
After 5 seconds you should be able to 'feel' the headphones at all. They should stop existing and you are left with the sweet blissful embrace of your favorite music.