Comment 2 for bug 1658970

All document properties are managed via templates, not preferences - they are specific to the drawing task (i.e. the file). You can create a custom user default template, and any number of more specific templates for new files with the preferred document properties (specific to the purpose of the template).

The current only exception is for default new grids, which is already problematic and not fully functional anymore, because the unit chosen for grid origin, spacing in the preferences are global, and do not adjust to the individual document's properties.