The problem is due to the fact that the new user account has a different ID than the old one, or perhaps the permissions of your user files were wrong before.
I suggest you modify the instructions you were given. Boot into Recovery (command-Rat startup), launch Disk Utility, and erase the startup volume with the default options.This operation will destroy all data on the volume. Quit Disk Utility and install OS X. When you reboot, you'll be prompted to go through the initial setup process. That’s when you transfer the data from one of your backups. For details of how this works, see here:
Using Setup Assistant
Transfer only "Users" and "Settings" – not "Applications" or "Other files." Don't transfer the Guest account, if it was enabled on the old system.
Reinstall your third-party software cautiously. Self-contained applications that install into the Applications folder by drag-and-drop or download from the App Store are safe. Anything that comes packaged as an installer or that prompts for an administrator password is suspect, and you must test thoroughly after reinstalling each such item to make sure you haven't restored the problem.
Note: You need an always-on Ethernet or Wi-Fi connection to the Internet to use Recovery. It won’t work with USB or PPPoE modems, or with proxy servers, or with networks that require a certificate for authentication.
