Hello Stephen,
All of the 'favourites' lists (favourite organs, favourite combination sets, and favourite temperaments) work in the same way in Hauptwerk in that:
- You need to load the relevant item first, e.g. via 'Temperament | Load temperament', or the 'Load ...' button on the 'Pitch' large control panel ('View | Large floating control panels ...| Pitch').
- Once the item has been loaded, you can then assign it to the desired one of the 'favourite' slots, e.g. using the 'Assign' button on the Pitch large control panel, or via the 'Pitch | Assign current temperament as favorite' menu.
I.e. you need to assign the desired item to the desired slot in the favourites list first, and thereafter it will be available to select from the favourites list.
The 'Selecting temperaments' section in the Hauptwerk user guide (pages 137-138 in the current v6.0.2 version) covers it.
There's no difference in v6 compared to v4/v5 in that regard, except that in v6 the number of favourites slots has been increased to 64 (previously it was 32), and v6 now also has functionality to edit (insert/delete/copy/paste/etc.) favourite assignments.