The attempt at a July 4th vacation trip to Big Bear doesn't turn out so well as issues with the kids overshadow the family fun. The teenagers have an attitude from the start, and as is not uncommon with teenagers, are pouty and pugnacious.
In the episode, most of the teens still feel traumatized to have had to leave Utah for Las Vegas. I can understand this — in Utah they were surrounded by a community of other polygamous families and a lot of others with the same or similar religious beliefs. The culture of Las Vegas is very different, and they feel isolated and unhappy.
You would think the fact that they have each other would help quite a bit, but the teens are at an age when they are coming into their own power, and are feeling their strength as a group. Their parents are going through a lot of personal issues, which makes more space for this rebellion. The parents are questioning the wisdom now of having timed the kids' birth such that so many of them are teenagers at once.
Hunter is particularly disrespectful, and seems to be causing his mother, Janelle, a lot of grief. His half-brother, Logan (the oldest son of the family), attempts to confront him but is also rebuffed. It appears from the series that Janelle is left to try to discipline him on her own, which I think is unfair — there needs to be more solidarity among the adults in dealing with these things.
Both of these boys remind us of aspects of Kody, naturally, and they are learning about how to be men from their father. Logan seems to exemplify the good, responsible side of Kody, while Hunter models himself more after the wilder side.