‘Silence’ on an object/PC/monster [closed]

Great insight on 'Silence' spell cast on a PC or object? , thanks! We are working with the Essentials kit, do not have the PHB yet so we don’t have the extra details/insight it offers. If ‘Silence’ cannot be cast on an object/PC/monster then can the Cleric move the point of origin based on the concentration factor or must the Cleric concentrate on keeping the same point of origin? Further, I’m not fully understanding why a point of origin perhaps cannot be something fixed like a rock or a fighter’s helmet given the fact that a Cleric is able to cast an Action spell while concentrating on the Silence spell. Thanks for your thoughts.