That's because Sony has never offered the option to change that PSN username, despite over a decade of frequent requests from users embarrassed over youthful name choices like "XxX_BluntMaster69_XxX". If for any reason you experience issues after changing your ID, you can revert back to your original ID for free at any time (you will only be able to revert once during the preview program). Subsequent changes will cost £7.99/$9.99, or £3.99/$4.99 if you have PlayStation Plus.
According to a recent blog post over on the official PlayStation website, "We're happy to announce that we will soon begin testing the long-awaited feature that will allow users to change their PlayStation Network Online ID from their PlayStation 4 system". Are you excited to be able to change that (admit it) slightly embarrassing gamer tag?
There is a catch in the fact that the name change is compatible with all games published after April 1st, 2018, and "a large majority of the most-played PS4 games that were released before this date".More news: Google+ shutting down following security bug
Here's the kicker, because with Sony there usually is one: the name change won't actually work for every game. The changes will be available in the Settings menu and Profile page on PS4. PSN users will also have the option to show their old ID alongside the new one, to make the transition more visible to online friends. The preview is set to end around November 2018, while full implementation is set for 2019.
Another caveat is that the new feature won't be compatible with all games. If you run into any issues with the change, PlayStation will let you revert back to your old ID free of charge.