Try putting him on his leash and attaching it to your belt. The key to housetraining is supervision – constant and vigilant supervision. When he starts to sniff or circle, tell him “outside” or whatever (but try not to startle him), and whisk him outside. If he potties outside, reward him with treats and praise as soon as he finishes – don’t wait ’til you come inside. If you discover an accident after-the-fact, don’t scold – it’s your responsibility to keep him from having that opportunity. Just clean the spot well and use an enzymatic cleaner to eliminate the scent. If you can’t directly supervise him, confine him to his crate or x-pen – every opportunity he gets to eliminate inside is a setback.