You can change the height of a fence, specify whether or not you want the fence to hug the terrain, edit the size and position of fence posts, and edit the dimensions of the rails and boards. See Parts of a Fence.
To edit the properties of a fence:
Click on the fence to select it.
Right-click and select Properties, or select Edit > Modify Elements > Properties.
To change the type of fence, click on the appropriate graphic in the Type area. Choose from General, Privacy, Picket or Ranch. The General style just inserts a plain, flat surface.
To change the height of the fence, edit the values in the Fence Height edit box.
If you want the bottom of the fence to hug the terrain, check the Hug Terrain? check box, then select either Raked or Stepped from the Slope Type drop box.
To change the dimensions or position of the fence posts, edit the post parameters in the Posts area.
To change the dimensions of the top, middle or bottom rail, edit the rail parameters in the Rails area.
To change the dimensions of the boards in a privacy or picket fence, edit the board parameters in the Boards area.
When you’re done editing properties, click OK.