You can see an overview of all of the files you have across your boards - just go to the 'All items' section of the app. Each item will have a label of which board it's saved to.
You can hit the select button and select multiple files to either move them to a new board, duplicate them, delete them, or export them if you wish!
This allows you to create new boards to transfer easily by grouping different files from different boards into a new board!
If you have any questions about this new feature or any feedback in general, just let us know!