There are several sites that go into detail about how to change permissions on files/folders, and this is the same process.
But referencing the attachment, right click the UserChoice key and select permissions. The top window opens. Then click the Add button and the bottom window opens. Type administrators in the box and then click Check Names. After you do, you should see your computer name\Administrators, as shown, except for the edits...
Then click OK, and the Administrators will be added to the users list. On mine, doing this added the other users and pretty well set the system up for use.
If you can, get a picture of the Permissions dialog window with it saying the permissions had not been set. I did not think to capture one. Use the snipping tool.
You can try just leaving it here and checking your operation, so just OK back out of the dialog. But if you want to get it back exactly, you can compare another UserChoice key, such as the one in .log for reference. I think the only other addition is the User is denied the ability to change the key directly, which should not be a problem.
If you have specific questions or problems, post back--with pictures.