First, you will want to go to your main dashboard and view your Trip list. Then, click on the Proposal or Itinerary you wish to convert.
2. On the right-hand side click on the drop-down option to Type then choose "Itinerary" or "Proposal". This will create a copied version of the Proposal into an Itinerary or vice versa.
Pro Tip: If you wish to keep a Proposal or Itinerary version you can choose the Copy option to create a new version of that trip and then convert it to the Itinerary or Proposal on the copied version.
For more information on Proposals and how they work, click here.