Everything entered on the page for the “Census assistant” itself (where you select and edit the names and their details) is part of the shared note.
If you want the Source and Citation to appear as a normal Source / citation, separate from the shared note (as I do) enter them on the first page in the process, which is the actual “Census event”. You can still enter them on the assistant page if you want. I don’t because it seems like unnecessary duplication, but others do it the other way round, or both. All personal preference, no right or wrong solution.