With PictureMe version 3.2.0, it is possible to reset the storage settings to default, using a button on the settings tab.
This function helps when something has gone wrong with the configuration and restores PictureMe to Factory settings.
In case an error appears before this button can be selected, you can also start PictureMe whilst keeping the Shift key pressed.
That also restores factory settings.
PictureMe 3.2.0 is available in the Mac App Store.