How do we go about contacting mods?

I am on mobile and I only see send feedback, I am not sure that is appropriate for what I need, and I might be blind with the desktop version.

I want to know if it is possible to change my username. I have had some problems recently with someone finding me on various platforms and even though I feel like I am safe here, I am getting a little paranoid. I have used this username on a few things, now changed.