Youtube on my Iphone can't access the microphone?

When I was prompted on wether or not I wanted Youtube to be able to access my microphone, I accidentally said no. Now I don't know how to change the setting to reverse this.

Why can't you delete the mobile youtube like delete it then re-install it through m.youtube.com?
i'm no computer pro or anything but mine always says get handler i can't even watch youtube. So goodluck?