Consistency is crucial. This may mean taking time off work to be there to take the pup outside every 20-30 minutes when they are awake. Crate training will also help the 'penny drop' as it teaches the pup to hold on until taken outside. Then, be sure to stay with the pup in the yard so you are there to reinforce how clever they are when they do go in the right place.
You should always accompany your puppy outside for potty breaks. You’re there not only to ensure that he actually goes, you’re also there to reward your puppy with a treat for going in the proper spot. Wait until your puppy finishes eliminating and immediately give him a tasty reward for a job well done. If you wait until you get back in the house, your puppy won’t make the connection between his elimination and the reward.
Be persistent! Make sure the puppy doesn't get the opportunity to pee and poop by using a leash indoors or confining him to a crate when you're out. Depending on the puppies age, pop him outside every 20 - 30 minutes, so there's a greater chance of him toileting outside (by accident at first.) In addition, get rid of any scent markers he's left by peeing or pooping indoors, as these will draw him back to the same spot. This means cleaning the area daily, for 2- 3 weeks after he last pooped there to fully get rid of any lingering odor that the dog can detect.
It's not so much the dog doesn't listen, more that he doesn't understand what you want him to do. Go back to basics and don't punish him when he toilets indoors. Double your vigilance and take every opportunity to put him outside to toilet. The crucial thing is to be present when he does toilet in the correct place, so that you can reward him. This makes him keener to repeat the performance to get another treat. Conversely, if you have been telling him off for indoor accidents he may already feel inhibited about going to the toilet in your presence, including when he goes outdoors. This is one reason why it's important not to punish for inappropriate toileting.
You can use potty training pads to give a puppy a place to go inside. They are usually scented in order attract dogs to urinate on them. This can be an aid in potty training and may seem necessary depending on your situation. But, it can also cause some problems that may prolong the training period and make it more difficult. Using pads can confuse a puppy into thinking that it is OK to go inside.
Young puppies can’t hold their bowels & bladders for long. If you come home to find that they’ve had an accident in there it’s quite possible that they can’t hold it that long. Generally puppies can hold their bladder for about one hour per month of age. So your 3 month old pup can probably only hold their bladder for about 3 hours. If you’re going to be away at work for long periods of time see if you can get a neighbor, relative or dog sitter to come over to let your pup out during the day.
Introduce your new pup to its new home, family and their role. Just like when you are new to a place or group, your new pet may be bursting with curiosity, excitement, fear or joy. Now is the best time to lay out the foundation for a good and pleasant relationship with your pet. For a puppy to settle in and learn to trust and respect you and everyone at home, it is very important to establish your expectations of your puppy and be consistent with them.
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.
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.