By Miles Nicholson
The video shows you how you can update a block on the fly from within a schematic. You might have created a symbol and realised once you have used it that changes need to be made or you may be working with an old drawing or a copy of an old drawing where a block is an old definition.
The Swap/Update Block command can update all instances of a given block with an updated version of the same block within either the active drawing or the entire project and it maintains the attribute values. Traditionally, AutoCAD® users would erase the block, purge the drawing of the block and then reinsert but this method loses the attribute information.
Select 
Select the radial Update a block – substitute new version for selected block
Select
Pick the block you wish to update
Select the radial Yes, copy all, old to new
Select (single drawing within the current activated project)
Select (multiple drawings within the current activated project)
The symbol block will be updated