Question About Grid Subdivisions

Question 1 : im trying to make the Grid Box subdivision into 4 only instead of 10 but no changes is made or update? a bug ? and it seems mine is disable … see picture

Solve : i need to be in blender unit

Question 2 : i want to maintain the opacity of grid subdivision when zoomed in

both main grids and subdivision becomes same opacity or black which adds confusion and unable to distinguish from one another

is it possible to maintain the washout opacity of grid subdivision? when zoom in like
2d application behavior ex. photoshop
thank you for answers