Unbundled song: one huge WAV file only?

Using CWPA 9, wanted to back up my songs onto a new laptop, so I made BUN files out of them. I opened one of the bun files on the laptop and then saved it as a new WRK file. But when I go into the WAVDATA directory on the laptop, I see only one big WAV file for this newly restored song. I was expecting to see different WAVs for each track, like on the old computer. When I open that big WAV file in Sound Forge, it has all my different track bits strung together, in no obvious order! Is this a reliable way to save a song? What if I want to work on it again? Can I still change something in just one track?

Or is there another (/better) way to back up my songs? Or a way to bundle & unbundle them keeping separate WAVs for each track?

Thanks in advance. I have years of WAVs cluttering up my hard drive, so any suggestions on how I can safely save and move all the good songs & tracks, and then get rid of all the leftover unused takes, would be much appreciated. At the moment I'm reluctant to hit "Clean Audio Disk" until I know I've saved all my good songs properly.

- Frank H.