Watch this video:

https://www.loom.com/share/a5bd85f5c46d4b699154b132084969dd

You can change the job address when starting a new proposal by clicking new proposal from the jobs pipeline. Or, for a proposal attached to an existing deal, you can click into the deal and edit the deal details to change the job address.

Each contact can only have one address but their deals can each have their own distinct job address.