Why does my notation come out in a different (higher) octave when I re-open the file than when I saved it?
And how do I change octaves generally?

I can't seem to find a solution in the manual - I actually had to re-enter the notation of a whole song to get the octave changed - there's got to be a simple solution to this.

I'm embarrassed to be asking what is most probably a stupid question, but what can I do ... I'll be grateful for any help!