When setting the default folder used for exporting files (primarily 'HTML' export):
- New documents open with the default export folder set to a folder in OS temporary folders. Preview will use this folder as a temporary export folder, and cleans up when the application is closed.
- Older documents will continue to use the previous default of
~/Desktop, unless a user-chosen location has been set.
The export folder may be changed by either:
- using the Export inspector's Export Folder button
- a button in the Export Inspector allows selecting to the temporary folder location (as the OS normally hides this from users).
- choosing File ▸ Export ▸ HTML and selecting an export folder
If the current choice of export folder is the temporary folder, choosing menu File ▸ Export HTML will invite the user to select a new export folder, rather than defaulting to the (hidden and thus confusing) temporary folder. Exporting to the temporary folder is not a useful thing to do, but is a boon when using internal preview/presentation.
A hidden factor underlying the changes from older behaviour are changes by Apple in internal security required for previewing Web(-type) content. As a result, notes need to be exported before they may be previewed. For a user doing internal preview, exporting files would require clear-up afterwards. By exporting to hidden temporary files, the zero-configuration of internal preview is maintained. Conversely normal (file export is able to work as before.
See also—notes linking to here: