I can set the paragraph spacing for new notes using the document settings. However, if I change the $ParagraphSpacing attribute of an existing note it has no effect. Once it’s set it seems to be set forever.
Is this a bug?
The $ParagraphSpacing attribute controls the spacing in (a) new notes, and (b) notes to which Format ▸ Style ▸ Standard Style has been applied.
To change the spacing in text that’s already formatted, you can show the ruler (Format ▸ Text ▸ Show Ruler) and adjust the line spacing there.
(If $ParagraphSpacing were applied elsewhere, you wouldn’t be able to change it for a specific passage.)