After changing the 2D extent of a datum, such as a grid or a level, use the Propagate Extents tool to use the same 2D extents in other views.
This video demonstrates the following:
Datums in Revit LT, which refer to levels and grids, can have both 2D and 3D extents. When a datum is set to use 3D extents, and the 3D extents are changed in one view, they are changed in all the views. When using 2D extents, changing the extents of the datum will only change the current view. The Propagate Extents tool allows you to set the 2D extents of datums in multiple views.
In this example, the grids in the East and West views are drawn across the building elements and need to be positioned above the building. When you select a grid line, the 3D icon near the end indicates that the grid line is set to use 3D extents. It is also constrained to the other grid lines in the view. As the end is adjusted, the constrained grid line ends move. Because the 3D extents are being adjusted, the grid line ends are also adjusted in the other elevation view.
Now the elevation views appear as desired, but since the 3D extents of the grid no longer intersect the levels of the model, they no longer display in the plan views. We'll undo the change to the grid lines to correct this problem.
To get the desired graphic appearance in the elevation views, and have the grid lines continue to display in plan views, the 3D extents must stay the same, and the 2D extents of the grids must be changed. Select a grid line, and click the 3D icon to change the grid to use 2D extents. We'll alter all of the grids in the view this way. Now the ends of the grids are again moved above the building, but this time only the 2D extents are altered, the 3D extents remain the same.
Because the change was made to 2D extents this time, the grid lines in the other elevation view were not changed. To get the extents to match in the other elevation, select the grid lines and then click Propagate Extents on the contextual tab of the ribbon. In the dialog, select the view where you want to apply the extents. Now both elevation views display grid lines in the same position, and because the 3D extents were un-altered, the plan view still displays the grid lines.
Use the Propagate Extents tool to quickly get the positions of datums in your model to match across multiple views.