I have customized Ubnutu but I want to upgrade to Kubuntu and save only some programs and configs
Back up the files you want, then download Kubuntu onto a disk/on your computer. Follow the easy on-screen steps to get and make the most out of it!
Edit: Wait, does it say 'Upgrade'?
You would upgrade to 12.10 and then install
If you are wanting to switch to KDE, it may be easier to simply back up your data and perform a fresh install.