Thank you so much for the response.
It is mostly poos that happen in the house. We take him out first thing in the morning and he always pees and poos outside. The problem is in the evening when we give him more freedom in the house. I try to take him out at least every 45 minutes and we stay for about 5 minutes or until I can tell he is not going to go because he is just playing.
We say "get busy Frank" for him to go outside, but I'm not sure that is working. He certainly doesn't go on command. I try to make a fuss about him when he toilets outside, but he doesn't care much when we are outside because he is so interested in other people/dogs, etc.
He will go anywhere in the house, not one particular spot. I think I should get the carpets cleaned though, because I'm sure he can smell all the prior toilets everywhere.
Keeping his leash on is a good idea. I think I'll try that and see how it works! Thank you.