Hello! We got a Bernese mountain dog a year ago thinking that training would be easy... (As they are usually a mellow dog) but have been having some major behavioral issues since about 7 months. He works great with me and my family (mainly me xD) but as soon as someone he hasn't seen for about a week or a stranger shows up he seems to forget all training and act terribly. He won't respond to any recall and even dog people start to hate him. My parents keep telling me, "he's a puppy" but I'm tired of his lake of good behavior and want to stop making excuses for him. Also, we live in a yard that is gates and have been able to teach him not to leave but as soon as he sees someone or smells something that's on the outside he runs out and won't come back. I need help with what to do now, if I should take him to classes or get something like a shock collar (I'd rather not) to teach him that what he is doing is wrong. Thank you!