I am glad you care enough to want to help your dog. What is his name? Sometimes people just try too hard to "bend" the dog
to suit some ideal to their own liking.Not a good idea really. Dogs are very perceptive, they can sense unease in a person & then they
feel uneasy. If you relax more when you are around him,take a cue from your grandson,don't try too hard & then get frustrated.

Sounds like he could be a very sweet & well mannered dog, given a chance to to learn. Give him a chance to see you as a relaxed &
confident person & he will notice and respond in kind.