Copy a Project to a different size, vendor or Aspect Ratio

File > Duplicate for different size copies the project at a new size, keeping the design. Pick the size, rename the copy, save it in your normal projects folder. The same flow moves a project to another vendor or a different aspect ratio. Going horizontal to horizontal, portrait to portrait or square to square usually lands almost identically; changing the aspect ratio changes how your photos are cropped, so BookProofs warns you to review the updated design on new project creation. To duplicate a project to the currently selected vendor and size, or to rename it under a different name, use File > Save As instead - it is placed in a new folder and also leaves the original project untouched.

Starts at 0:41 in the project size videoWatch on YouTube