Style sets frustration

[jmckeown]

In principle I am keen on Style sets but in practice they cause me lots of trouble.

For example, at the moment in "Edit Style Sets" I can see my styles: Default, Screen, Draft Print, Final Print, and Screen variant.
But the drop-down Style Set menu only offers 3 out of 5. Why does one part of Mellel know about all 5 but another not?

Sometimes when I start a new document Style Sets have disappeared. Are they tied to a document, or system-wide?

regards,
J Mckeown