Hi friends,
This question has come up a couple of times recently at the helpdesk, which typically indicates that more folks would like to know the answer
The default display for both Notation Musician and Notation Composer of the Drum staff of a score is with x and triangle noteheads. The x, empty triangle or filled triangle indicate the pseudo-pitch MIDI drum notation, which is what drum instrument is playing at a particular point in time.
DrumInstrumentOn.png
Some folks find that to be more confusing than using regular noteheads. If you prefer the regular noteheads notation, simply uncheck the "Drum instrument" box in the lower left of that staff's Staff/Setup dialog.
DrumInstrumentOff.png
Enjoy!
Sherry