Windows Store doesn't let me upgrade to 8.1, says I am not administrator

Question

Hello, I am trying to upgrade my Windows 8 to Windows 8.1 with Windows Store. But Store refuses to let me download, saying I do not have administrator rights. I am with an administrator account and a ms account login. But it still doesn't let me. I
put UACs at minimum. I tried creating a new admin account, same problem. With the integrated account Administrator, which was desactivated, I can't access Store at all. I did all the updates, I ran a MS FixIt utility to checkproblems with Windows update,
it fixed nothing.....
How can I upgrade to Windows8.1? Actually my question should be, how do I give myself the rights to do it?
I am really not happy of not having rights on my own machine.
Thank you for your help. I am really lost here :)

Answer 1

Try this it worked for me
First, find where all the updates for windows are listed.  Go to Control Panel ---> Programs.  Then under Programs and Features, you'll see a link called "View Installed Updates".  Under Microsoft Windows, scroll until you find KB2871389.
 Uninstall it, and then accept the prompt to reboot your computer.
Now, login under your account (that has admin privileges) and then go to the corner until the floating menu comes up and choose settings.  From settings choose change PC settings at the bottom.  Then, click on "windows
update" at the bottom of the right hand side of your screen.  Check for updates now and it will take a few minutes, but they will find one (KB2871389).  There
is a message telling you that it will download automatically in a few days, but ignore that, click on the link for one important update, and choose install now (or some such thing). 
Log in on an admin account, go to the store, choose the 8.1 update, and now, no admin problems.
I had exactly the same problem and this worked a charm!
I was unable to install 8.1 despite using my Admin account, but this fixed it.
But I worry for anyone who doesn't have tech knowledge, because this is the last thing in the world anyone would consider trying.