MuseScore -- Index -- Beams

Beam pallete

Beams are set automatically but the automatic setting can be overridden manually. Drag a beam symbol from the beam palette to a note in order to change its beam behavior.

You can also first select a note and then double click the appropriate symbol in the beam palette.

Start beam button    Start a beam at this note.
Middle of beam button Do not end a beam a this note.
No beam button Do not beam this note.
Second level beam button Start a second level beam at this note.

See also: Cross staff beams