Seeking professional help doesn't mean ditching your DIY training program. You can find a professional dog trainer who offers private training sessions, and some trainers even offer online sessions. Many dog owners prefer to join a local dog obedience class so they will be under the supervision of a dog training instructor without the higher cost of private sessions. Plus, classes challenge your dog to learn around the distractions of other dogs.
Accidents will happen, and it’s important to clean them up thoroughly. Dogs are attracted to spots that they’ve used previously, and remember that their sense of smell is way better than ours. Pet urine can be hard to get out, and not all household products will effectively remove odors. If your dog keeps going in the same spot chances are some of that smell has been left behind. You can opt for a product that’s formulated for removing pet urine odors & stains.
I don't teach or recommend so-called "purely positive" methods that allow misbehaving pups to continue misbehaving, instead of teaching them which behaviors are and are not allowed. "Purely positive" is fine for teaching tricks and high-level competition exercises, but NOT for teaching the solid good behaviors that all family dogs need to know, and NOT for stopping behavior problems such as barking, jumping, chewing, nipping, chasing, etc.
It’s best not to punish the puppy for making a mistake. Instead, focus on praising appropriate bathroom behavior. If you catch your puppy in the act, interrupt it by saying “No!” in a firm voice or clapping your hands loudly, then take the puppy outside to finish going to the bathroom. Never swat your puppy, yell at it, or try to rub its nose in the mess.