Sensitivity lower than should be

I have my sensitivity set to 100 yet when I see YouTube videos of people with the same sensitivity settings it seems so much higher than what mine is, and I haven't seen any with the same settings as me and same gameplay so I have come to the conclusion that it is an issue for a handful of players. Please try to understand my issue here as the game is a little hard for my liking with this bug, although I do understand if it is unfixable.