Terrain Brush editor bug?

Everytime I try to lower or raise the terrain on my map a brush is bugged in 1 spot constantly, and it's quite annoying honestly. Any way to fix this? If I need to make the terrain heightmap -1024 -1024 to fix it, can you tell me where i find that?

Video of my problem..

 

make sure you terrain is in the postion that its size is. so for example if you terrian is 1024x1024, set the position to 1024 1024 X(dont change this third value)

 

And where do I edit the position? I don't know where it's at.