Do you know how to reset all the metadata views back to their default designs?

The metadata view settings are kept in the user's Application Support folder. If you delete the file MetadataSets.plist, Aperture will create a new one with the default settings.

The Application Support folder in the Library which is inside the user's home folder. Aperture has its own folder. Mine looks like this:


This is also the home of many other settings for Aperture, including the keyword list, watermark images, and plug-ins. Sometimes these files are the cause of mysterious crashes on launch, so it can be a good test to rename the folder and relaunch Aperture to see if the problem goes away.

All these settings only apply to this user, note. There is another Application Support folder with an Aperture folder inside the Library on the boot disk. Here is mine:

BorderFX is here because it has an installer that put the plug-in in this central location. This gives access to the plug-in to all users of the machine. On my machine the Sample Projects folder is empty. That's because I trashed its contents after I had played with the images provided. It's worth checking to see if yours is wasting space and trashing the contents if it is.