Being 60 years old, I personally have seen the moral change in people over the decades, from just being disrespectful to now outright murder of one's parents (such as Tyler Hadley in Florida, who murdered his parents in 2011 with a hammer when he was 17, then threw a house party 3 hours later or of Daniel Petric in 2007, who at 17, shot both his parents [killing his mother] because his father had taken a violent video game called Halo 3 from him or of Noah Crooks in Iowa, who at the age of 13, shot his mother 20 times [and also admitted to trying to rape her] because she had confiscated his video game Call of Duty in 2013) as well as of others.
Jesus said that our time period would be characterized by lack of love, saying of his invisible "presence" (Matt 24:3, Greek parousia, not erchomia meaning "coming", that began at the beginning of the "Lord's day" in 1914, Rev 1:10), that "because of the increasing of lawlessness, the love of the greater number will grow cold."(Matt 24:12) Indeed, love has "grown cold", and not just with teenagers, but all of the restless masses of mankind, "the sea".(Isa 17:12; 57:20; Rev 21:1, those who are "restless" for change, never satisfied)
This lack of love that truly began to accelerate since 1914 (when Satan was thrown out the heavens, Rev 12:7-9) is now in freefall, gaining momentum like a snowball rolling down a hill on a snowy day.(Rev 12:12, Satan knows that since his eviction from heaven, he has "great anger", because he has a "short period of time" before his being abyssed for a 1,000 years, Rev 20:1-3)
Teenagers are more than disrespectful, but arrogant, and at times threatening. Many who are immigrating to the United States, have vividly pointed out the violence among teenagers in their home countries of Guatemala, Honduras and El Salvador.
We are living during an era of rapid change, especially morally and of which teenagers are being infected with the "spirit of the world" that displays itself in loveless or hateful or wicked acts.(Eph 2:2) Twenty year old Adam Lanza showed such a wicked disposition, gunning down 20 children and 5 adults at Sandy Hook Elementary School in Connecticut in December 2012, after having murdered his own mother.
The apostle Paul calls these times "the last days" and describes them as "critical times".(2 Tim 3:1) In using the expression "last days", it shows that they are limited in time, that they will soon come to an end, for Jesus paralleled his invisible "presence" to the "days of Noah".(Matt 24:37)
The 120 years prior to the global deluge were surely wicked (Gen 6:3), for Jehovah God said: "Consequently, Jehovah saw that man’s wickedness was great on the earth and that every inclination of the thoughts of his heart was only bad all the time."(Gen 6:5)
But just as the wickedness that existed then among mankind was vanquished (Gen 7:21), so likewise our Creator has set an appointed time soon to remove all the wickedness that is in every nook and cranny on the earth. It is called Armageddon, the "war of the great day of God the Almighty".(Rev 16:14, 16)