Yeah - this is a nightmare. If you realise you decide to use a new control, or realise you've forgotten one, you manually have to retick dozens of boxes and there's no way to find out what you previously had before (or what controls you're physically using).  It would be better if the download link took you to a new page, with the selections saved in the URL and included that URL at the top of the actual JS bundle with a note about how to change selections.

It would be nice if we could save the items\builds back to our telerik accounts so we can keep separate builds for separate projects.