Terrain sculpting

I’m having a problem with sculpting.
I can’t seem to sculpt anything under like 1k brush size. I want to make small mounts and such like this

When I sculpt my terrain it’s raising with like ridges like this

I want to to come up smooth but I can’t seem to find out how.

Everything is raising by like… It’s corners or something: Screenshot - 85dd8d6e5fdb2dd5971602d27e34f00e - Gyazo

I can’t raise the terrain thin the middle of that, it has to be on the “corner” of that square.