Sharps and flats
Sharps 
, flats 
and naturals 
can appear in music in different ways:
- As fixed signs to a (part of) a melody. These signs apply throughout the rest of the melody, up to a possible key change. Sharps and flats as accidentals are directly linked to the key signature.
- As accidental increase or decrease (to be entered with <+> and <->). Notes that are not proper to the scale get a sharp, flat or natural, depending on the key. The note G#/A♭ is much more often written as g# in the key of Am, while it is notated as a♭ in Gm; each tone has a preferred notation or spelling in a key. You can deviate from this preferred notation by using enharmonic exchange you instruct MusiCAD to write a note "the other way". You indicate enharmonic exchange with <x>. Remember to specify the correct key before working with enharmonic exchange...
Besides 'normal' sharps and flats, there are double sharps 
and double flats 
. An accidental raising of the (proper) note f# in the key of C# should usually be called f## and should be written with a double sharp 
. For example, every note (except the G#/A♭) can be 'spelled' in three ways: c = b# = d♭♭, c# = d♭ = b## etc. Using the accidental menu under the double flat you can you can easily implement such an alternative enharmonisation.
A strange duck in this bite are quartertone increases and decreases.