The Options dialog box in the Tools menu allows you to customize many of the things about the Opus environment, including the colour of the grid, whether the Properties dialog box appears automatically, the default colours and fonts for text, and so on.
The Options dialog box contains an Options Organiser on the left-hand side of the dialog that provides an Explorer type view of folders containing the options you can edit. The options themselves are displayed in the right-hand side of the dialog.
the General (More) tab - Options
the Defaults (More) tab - Options
the Grid and Outline tab - Options
the Default Font tab - Options