If you use Microsoft authentication when creating a new user, you can end up with an inconvenient user folder name. This can be changed as follows:

1. Login as a user with administrative privileges.
2. If necessary, rename the the user. (Win+X, G (Computer Management) → System Tools → Local Users and Groups → Users, right-click user, Rename.)
3. From the command prompt rename the user folder. (Win+X, A (Command Prompt (Admin)) and ren C:\Users\oldname newname)
4. Now use the registry editor to change the path for the SID of the relevant user:

• Win+X, R (Run)
• regedit
• Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList\
• Click onto each SID and check ProfileImagePath for the old folder name (e.g. c:\Users\oldname). When you have found the relevant SID, change the value for ProfileImagePath to the new folder, e.g. c:\Users\newname

Login using the new username and check all is working correctly.