[FirstYorkie]

Here are two things to try:

First, dogs often stimulate themselves to "poop" by smelling old feces. Pick up a piece of feces with the pad you want him to use, discard the feces, and use the pad. A bit of the smell will remain and will remind him "this is the place for poop".

Along the same lines, be sure that you are using a special enzymatic cleaner for accidents. Otherwise, the smell remains which says to the dog "poop here!".

Second, you've already worked out that reprimanding a dog for pooping in the wrong place doesn't work. It leads to a dog who decides that it isn't safe to poop when you are around. If you find an accident after the fact, sigh heavily, say nothing, and vow to watch them closer in the future.

If you catch them in the act of pooping in the wrong place, don't yell, just say "no", pluck them up and carry them to the appropriate place. If they finish in the right place (or you catch them going in the right place) - throw a party! Lots of high-pitched, excited praise and yummy treats. Dogs learn much faster when you teach them what you want (you get rewards if you do this) than if you try to teach them what you don't want (you get in trouble if you do that).

Good luck!