It’s really simple import and export all saved thank you pages.
1. Go to the plugin settings and open the Import/Export tab
2. Click on Download current plugin settings button, to generate a .dat backup
3. Click on Import plugin settings and select the .dat file, to import your backup.
4. Click on Restore plugin settings to delete all pages with a single click.
Here a videotutorial that will help you to import and export your custom thank you pages.