I had a weird superstition about changing my horses' names when I got them, so I tried to keep the changed name similar. My gelding was named Kokomo (which I despised), which I shortened to Koko. My mare was Cherie, which I changed to Cherry.
But now I have a chestnut named Koko (everyone thinks it's Cocoa) and a bay named Cherry, so everyone gets them mixed up.
I was able to track down some of my mare's history and found out that she used to be named Ginger (a few years ago). I tried it on her one day, and she remembered it! But I'm sticking with Cherry at this point, even though Ginger is actually a more suitable name for her.
I generally try not to change barn names ever, and change show names only if they completely set my teeth on edge. One if my horses can with a show name I hated that wasn't 't his jockey club name, so I changed his show name to his Jockey Club name. The two exceptions to my don't change the barn name policy was a youngster who had been named "Little Spooky" by the breeders 10 yo daughter, and a quasi rescue whose previous owner told me her name was a disgusting word for female anatomy that starts with a "C". They became Oscar and Matilda respectively.
My favorite name story is a friend of mine with an OTTB called Klink. No , not a Hogan's Heroes fan, but rather when she went to the track to look at him the trainer said she was selling him cuz she "needed the money to bail her man outta the Klink". Lol!
I change the names of my lot all the time. Sometimes a name sticks around - like joePony for example (who was Grey Traveller, barn name Nitro when he arrived) who has been joePony (small j, capital P) for years. Some of them change names more often than I change underwear. Pete, for example, only came in for 60 days training, and he became Bob within about a day. And his real name is Matton Majestic, so if he was to have yet another boy's name, you'd think I'd have picked Matt. But no, he's Bob.