After modifying a 2D datum to the desired extent, you can choose to have the datum look the same in similar views.
 Video: Propagate the Extents of Datums
 Video: Propagate the Extents of Datums 
You can use Propagate Extents to accomplish this.
To propagate 2D datum extents
 Datum panel
Datum panel
 (Propagate Extents).
 (Propagate Extents). 
There is no permanent connection between the look of the datum in multiple views. If you modify the datum again, you must use Propagate Extents again. Propagate Extents does not affect Model (3D) extents.