.Choose Construction > Grid Preset
.
Drag the mouse left and right to resize the grid.
or
Type the new distance between grid lines.
Choose Construction > Grid Preset
to customize the grid further. For example, you can turn on Labels to show distances between grid lines.
.
.
.I want to change the current unit of measurement?
To change the units of measurement set the Units modeling options in the Construction Options window.
I want to use the grid on a plane other than the ground plane?
Create a reference plane and set it as the construction plane.