This is what I do

Charms bar >Settings> Change my PC settings > User > "Trust this PC"

When I get my Code via Text, E-mail, or Phone Call I am taken a screen that says

Visit https://account.live.com/trustdevice on Internet Explorer from the Windows 8 device you would like to trust.

But I am already in Internet Explorer 10. I have tried to do it on the desktop version of Internet explorer but I unsuccessful.

I have refreshed my PC from Windows 8.1 preview back to Windows 8 because of unfixable bugs in the preview.

The only problem I have left is that I can't trust my PC.

Open Internet Explorer and type the following https://account.live.com/trustdevice into the browser bar - hey presto I received a message saying "thank you for confirming your identity" - or something similar.

This was after I had requested and input several codes and also ticked a box asking the PC not to ask for any more codes.