Bar
Adding and removing measures
"+" adds a measure after the current one; F8 I inserts before it instead; Ctrl+Delete deletes the current measure or selection.
Barlines and repeat signs
A repeat pair needs both ends set independently — a begin-repeat on the measure that starts it, a repeat-end on the measure that ends it.
Changing clef mid-score
A clef change is a normal, fully-supported mid-score edit — the new clef stays active on that staff from that point forward until the next explicit change.
Changing time and key signature
F8 T opens the time signature picker and F8 K opens the key signature circle of fifths — both apply from the selected measure forward.
First and second endings (voltas)
A volta brackets which measures play on a given pass through a repeat — select the range first for one keypress, or enter volta mode with no selection and navigate to the end.
Jumping to a measure or rehearsal mark
Ctrl+G opens Goto — type a bar number, or pick from a merged list of named sections and rehearsal marks, to move your cursor there instantly.
Segno, Coda, and D.S./D.C. markers
F8 N toggles Segno, Coda, and Da Capo/Dal Segno markers at a measure — playback actually jumps on them, resolving repeats and codas the way a performer would read them.
Splitting a score into sections
F8 S marks a titled heading within one continuous score — a forced system break, an optional title/subtitle, restarted bar numbering, and per-part staff visibility.