A number of useful commands can be found in the Edit → Tools submenu.
This tool adds or removes system breaks (Line breaks prior to version 2.2) over all or part of the score:
Chose Edit→Tools→Add/Remove System (Line) Breaks…. The following dialog appears.
Chose one of the following options:
The explode command allows you to select a passage of music in a single staff and split (explode) the chords into their constituent notes. The top note of each chord is retained on this "source staff" while lower notes are moved to subsequent staves. Explode only affects notes in voice 1.
To explode a section of the score:
Notes: (1) MuseScore will discard the lowest note(s) of any chord that contains more notes than the number of staves in the selection. (2) If a given chord has fewer notes than the number of destination staves, then notes will be duplicated as needed so that every staff receives a note. (3) Any existing music in the destination staves is overwritten. (4) If you select a partial measure, the explode command will automatically expand it to a full measure.
The Implode command works in the opposite way to "explode":
Note: Implode works best if the rhythms of selected underlying staves are similar to that of the top staff—the latter providing the rhythmic template for the operation.
The voice 1 notes of underlying staves are copied to the top staff in the selection.
All selected notes in the staff are now displayed in voice 1.
This command fills the selection with slashes, one per beat:
If a measure is empty the slashes are added to voice 1, full-sized and centered on the middle line of the staff:
Notes: (1) If there are already notes in a measure in the selection, the command will put the slashes into the first available empty voice. (2) Voice 2 slashes are full-sized and centered on the middle line of the staff; voices 3 slashes appear small and above the staff; voice 4 slashes are small and below the staff. (3) If a measure contains notes in all 4 voices, voice 1 will be overwritten. (4) All slashes are set to not transpose or playback.
This command toggles selected notes between normal notes and rhythmic slash notation:
The selected noteheads are changed to slash noteheads which do not transpose or playback.
Slash-notehead notes in voices one or two are fixed to the middle staff line; those in voices three or four are small ("accent" notation) and fixed above or below the staff:
In percussion staves, notes in voices 3 and 4 are not converted to small slashes but to small notes above or below the staff.
The Resequence Rehearsal Marks command allows you to re-order the numbering/lettering of rehearsal marks if, for any reason, they have got out of sequence. For details see Automatically resequence rehearsal marks.
This command, available in MuseScore 2.0.3 and above, copies all the lyrics of the score to the clipboard: