You can input key signatures using the Key Signatures options on the Symbols tab. Key signatures are markings that show the current key of music by indicating which notes in the scale for the corresponding key are sharpened or flattened. They are shown at the start of each system, on every applicable staff.
Procedure
Result
The key signature is shown in the score display, and all notes that you subsequently input follow the key signature.
Note
The Music Font that is selected on the Fonts page of the Score Settings dialog is used.
If you input a key signature that does not show accidentals, such as C major or A minor, this is indicated by a signpost.