+1 bump 
Pretty common to have English audio + subs as the default, but have many, many series (such as Japanese audio + English subs) where it breaks the pattern of preference.
Still very very awesome that we now have per-series overrides implemented, but it would be so much faster when managing many series at once if a Library default could be chosen, especially since “Library default” is already an option for other settings. I can’t imagine this would be hard to implement (maybe that’s naïve), and clearly there’s community desire for such a change
