Save render layers to separate image files

I render multiple passes and  combine all in photoshop.

Right now, I use File Output node and  Add New Input Slot  in the properties of the node in Compositor to render them all separately.  I saved file as startup file so that I don't have to repeat the process for all passes every time I render.

Is there any other simple way to export each rendered layer as its own image?

Save all Images is always disabled in Image Editor . How do I enable it and Can I use it to save all passes ?