Youtube won’t let me change my name!!

I keep trying to change my name but every time I do it just says “try a different name, this name cannot be used” or something along those lines. The name i’m trying to put it not inappropriate at all, and i’ve tried multiple different names and they all say the same thing. it’s been well over 14 days since i made this username. I’m very confused!!! How do i change my name??