when I press the "page up/page down" keys, if the
staff I am switching to is shorter than the one
now the insertion point jumps to that staff's end,
also when I change the "page setup" settings and
just switching tabs in that dialog box, the
insertion point jumps to the beggining of the
song, not to mention changing staff size
and margins
Yes, both are annoyances. The movement from one staff to another can be solved by keeping your active staffs all together (they can easily be moved up or down), so the short staffs aren't in between. You could always add bars of whole rests to each short staff - but it's a pain because you have to find a way of remembering why you wrote them in.
Consider changing staffs with the mouse pointer, rather than ctrl-p.u.
I've seen this problem myself, and yes, it is quite an annoyance. however, I realize that MS applications, in particular MS Word, behave the same way. when you are scrolling between lines of text, and from a longer line to a shorter line, when your cursor is at the end, then you'd be moved from the farther right side to the middle side of the document, or up to where the short line is. based on this, I'd say that this annoyance can be lessened, but not totally eliminated, in a way as David suggested. i've lived with it in v1.75b.
i was actually wishing it would keep its screen position, but in reference to what? a non-existent stave? now that would be something!
Where I wrote
"You could always add bars of whole rests to each short staff - but it's a pain because you have to find a way of remembering why you wrote them in."
A memory trick would be to highlight the extra rests in the now lengthened staff, and change their colour.
When doing full scores it is sometimes helpful to first create a staff with all barlines and rests, and copy/paste this to all of the as yet unwritten parts.
For example, you have written 1st trumpet (ALONG WITH ALL articulations, dynamic markings, etc), but copy and paste rests and bar lines to the 2nd, 3rd, 4th trumpets.
Then when you are filling out the score, copy and paste a section from the first trumpet onto the same section on the 2nd, 3rd, and 4th parts (or any other instrument that is Soli with the 1st trumpet part).
Next, you highlight to select the section you are harmonizing in the second part, and using Ctrl+Shift, then arrow, move the 2nd part notes up or down. Yes, they will not all be shifted the same amount, but you can get the majority of notes right. Then using the same technique, shift the remaining notes (highlight to select, Ctrl+Shift, then arrow up or down to move).
Use the same technique to move the notes of the 3rd, then 4th parts. You are really speeding up your scoring now.
Is section [D] the same as section [A]? Copy and paste each part to the appropriate measures in the latter part.
Section A, highlight to select, Ctrl-C to copy... go to Section D, highlight to select the appropriate measures (which are now just rests and barlines), Ctrl-V to paste.