Staves size and spacing between staves and systems
To customize the staves size and margins between staves and systems, open the Layout Settings. The tool is available in the Document toolbar.
Under the Staves settings you can edit the Size of the staves, and the distance between the systems and staves.
The preset sizes for the staves are the standard Rastral Sizes, but you can also customize them by specifying your own size in millimeters (mm).
It's important to remember that the layout algorithm evenly distributes the empty space on the page between the systems. This means that if you decrease the space between systems or staves, you may not see an immediate change unless there is sufficient empty space to accommodate another system on the page.