My dog would always pee when someone came over. He grew out of it eventually, when he was five
. Assuming you don't want to wait that long I'll need to know a little more about when he does this. Tell me all the situations that will make him pee inside. You said he does it if you say no, so stop saying no. Some dogs are so submissive that using any harsh words makes them fall apart. You can probably use a no reward marker which you will have to teach to him instead of no. I HIGHLY recommend the book The Culture Clash by Jean Donaldson, very, very good book and it will teach you no reward markers and how to teach them.
If he pees when people come over then make sure you take him out to the bathroom and he pees before they arrive then put him in another room when they do, before they come in. Once everyone is in and settled then let him out to see them, make sure they pay no attention to him until he is calm. Once he is calm then people can CALMLY pet him, don't make him excited since that will make him pee.
Now does he only pee inside when he is excited and scared or does he still have accident o other occasions? If he still has accidents then start crate training if you are not doing that already. Crate training is basically whenever you can't be watching the dog he goes in the crate. The dog will not pee in the crate so that way you can prevent him from having unnoticed accidents.
I personally don't like the puppy pads because they can be very confusing to the dog. It teaches the dog that it is ok to go inside. If you take the dog outside to go potty there is a very clear difference between inside and outside, where not to go and where to go potty.
Explain the situations he submissive and excited pees in exactly and I'll see if I can help you more in each situation. And please get that book I recommended it will teach the no reward marker and will teach you positive training which is essential or any dog but even more so for yours since he is so submissive.