Changed Username, Broke Everything

Thanks in advance to anyone who can help! I changed a username in Yosemite, and now everything under that username is wrecked. Chrome won't work at all, saying it can't read or write to a data file. All of my son's Minecraft data is lost, and the minecraft launcher won't run, saying something about Java not being able to set up a directory. Both these things run fine under all other usernames. Also, I can't establish Read/Write permissions for any folders at all, though the problem username is an admin account, and I have all the passwords to unlock the permissions manually and changed them in the "get info" area, and have changed them many times, the change never sticks. I have tried Repair permissions, in the disk utility, and that hasn't worked either. Why do they let you change your username if this is what is going to happen?