Thanks for that. I guess that with all the other foibles in Evernote* I'll just have to take it 'as is'. It is just too troublesome to find a way to make a synced encrypted notebook local every time I open it or make a change. I'll just assume that once it is re-encrypted the un-encrypted version is permanently deleted from wherever.
Incidentally, I I'm sure that I had encrypted notes before I upgraded to Plus.
Cheers, Colin
*I've been using computers for more than 30 years and I've never had an app that was as once as useful as Evernote and has so many blinding faults. Its typographic inconsistency [expecially cross-platform] is mad, it would not matter if it did not offer all the choices on a desktop, only to have them trashed if you open a not in iOS or Android. Also I paid for Plus to have offline access to notes, only to get [an incorrect] error saying I could not open a Note as I'd not opened it before. But above all it is the inconsistency of features cross-platform which is greater than any other app I know.