I'm in Windows 8, Lightroom 4.3
I have a set of User Preset exports.
It took me a long time to figure out why the changes that I was making to the presets weren't working and that if I wanted any changes to stick I would have to "Add" and create them under a new name and that there is no editing despite there being dropdowns. I was expecting that after a preset had been made, I could make an edit and then click the export or make an edit and then move to another user preset and the changes I'd made would save. If you want to keep that there should be no editing, it would have been more obvious if all the fields had been non-editable or there had been some "override" checkbox.
As long as we're on the subject. The selected item on the left loses focus once you start editing and there is no title at the top of the edit form, so you can't tell the context of the edits you are making when you are making them.
Perhaps this screen should go through some more usability testing.