upgrade to windows 8.1

I purchased a new computer laptop that came installed with windows 8.0 . I want to upgrade to windows 8.1 as it runs much better than windows 8.0, I was told and it is free I was told . When I try to download the update to windows 8.1, I get the following message : "You need to use an account with administrator privileges to install Windows 8.1 ,try logging in with the user account of AN ADMINISTRATOR of this PC and trying the upgrade again " ???
I am the administrator , so how do I let my new computer know ??
Thanks Rick F