You can change the default staff-relative placement of all figured bass figures 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 staff-relative placement of figured bass.
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 Players.
In the Figured Bass section, choose one of the following options for Default placement:
Above staff
Below staff
Click Apply, then Close.
Result
The default staff-relative placement of all figured bass figures in the selected layouts is changed.
Tip
You can also change the staff-relative placement of individual figured bass figures by selecting them and pressing F. If the property scope was set to Locally, this change only takes effect in the current layout and frame chain.