Secondary brackets extend beyond brackets, allowing you to mark groups of staves within a bracketed group. You can show secondary brackets as either braces positioned outside the bracket or as sub-brackets in each layout independently.
Procedure
Press Ctrl/Cmd-Shift-L to open Layout Options.
In the Layouts list, select the layouts in which you want to change the appearance of secondary brackets.
By default, the layout currently open in the music area is selected when you open the dialog. You can select other layouts by using the selection options in the action bar, clicking and dragging across multiple layouts, Shift-clicking adjacent layouts, and Ctrl/Cmd-clicking individual layouts.
In the category list, click Brackets and Braces.
Choose one of the following options for Secondary bracket appearance:
Brace
Sub-bracket
Click Apply, then Close.
Result
The appearance of all secondary brackets in the selected layouts is changed. This includes secondary brackets in custom bracket/brace groups.
Note
Because you cannot show sub-sub-brackets in addition to braces, sub-sub-brackets are not shown in layouts where sub-brackets appear as braces.