I brought this a week ago. When the salesman helped me set up, he set the user name "User_" which i later changed to "Anthony Tsang". I now see Anthony Tsang in the login screen. However, in the C drive, it is still "C:\User\User_". It's very annoying. How can i change it from "C:\User\User_" to "C:\User\Anthony Tsang"?
I tried control panel, there is no "Local Users and Group" option in the accounts manager page.

From your description, I understand that you want to rename C:\User\User_" to "C:\User\Anthony Tsang". I will be glad to assist you.
We cannot rename the profile with which you have logged in. We will create a new user account with user name Anthony Tsang and transfer the settings from old user account to new user account.
To create a new user account, refer to the suggestions from this link:
http://windows.microsoft.com/en-IN/windows-8/create-user-account
To transfer the profile settings, follow the suggestions below:
a. Log on as a user other than the new user you just created or the user that you want to copy files from.
a.Press Windows and x together and select Windows Explorer.
b. Click on View tab and Click on Options at the top right corner.
c. Click the View tab, and then click Show hidden files, folders, and drives.
d. Uncheck the box which states Hide protected operating system files.
e. Click Yes to confirm, and then click OK.
f. Now navigate to C:\Users\User_\
b. Copy all the files, except these three files NtUser.dat, NtUser.ini, NtUser.log.
e. Navigate to C:\Users\Anthony Tsang\
f. Paste all the files here.
Restart the computer and login to Anthony Tsang and check.
Once you are confident that all the settings and data are transferred to the new user account, you may
delete User_ account.