Aren't Springers sneaky?! Before you know it they ruling the roost and you're standing around wondering how that happened!
I would like to suggest dog obedience to you. I have 2 Springers and have taken both of them to a local obedience class for training. (Frankly, I think the humans are the ones who get trained without even realizing it!). A good trainer can make such a difference for you and Marley. It made a huge difference for us. Look for one that is run by a local dog club. Personally, I would stay away from the classes that the pet shop has.