Potty training an older dog.

Hi,we adopted a cockapoo a week ago. Sammy is about 1 year old. Our home is his fourth. Everything is going well with him, we are very happy. Sammy is a really cool dog although e has accidents in the house 1-2 times a day. I take him out at least every 2 hours and when he pees or poos, I praise him and give him a treat. I am thinking that since he has been bounced around so much that he was never taught properly. He does not give me any signals when he has to go, such as whining by the door and such. Has anyone on this forum ever adopted an older dog with a potty problem, if so what were the results? I am hopefull that he will learn soon.