From MusiCAD

Text objects, symbols and slurs can be resized. That adjustment is in addition to the text size associated with the text type.

<ctrl +> size-plus Make cursor object larger. Applies to text objects and crescendi and slurs.
<ctrl -> size-minus Make cursor object smaller. Applies to text and crescendi and slurs.

In the main screen the buttons are linked to the layout templates for resizing the entire score.

See also