Blocks are best utilized on sketches that may be reused or when sections are going to be repositioned

Once a Block has been created, it is now effectively a single entity.  This entity must be defined as any other.  To edit the contents of the block, RMB→Edit Entities→Make adjustments→Check-it-Out

To revert the Block back to its base-entities, RMB→Explode Block

Generally you can lock a position coincident and add an angle to fully define