What do to with a dog that pees everywhere

I have a dog that I’ve had for 3 years, I got him from a family that was giving him away. Ever since we got him, he just pees everywhere, we take him outside but he still pees inside, I’m not sure if his past owners trained him to pee outside. But there’s also a thing about him, when we got him, he was really scared of any adults that were in the same room as him, I’ve tried my best to accommodate him to the present of any adults but it doesn’t work,I’m at my wits end but I still to help him.