These furbabies sure have strong wills and just when you think you're making some headway, they regress. Skinbabies do that too.
Puppyhood is challenging.
If you can catch Riley in the act of pooping and say "no, no, no-o-o-o" while picking him up and bringing him outside, it could help.
Is he confined to certain parts of the house? Puppy-proof the house because they're curious about everything. Why not, there are so many interesting things to investigate.