Custom Chord Symbol Suffix Library

I suggest you review this other recent thread:

Edits you make in Library > Chord Symbols can be saved as defaults for all future projects by selecting the chord symbol appearance you want to save, then clicking the star button in the action bar at the bottom of that list on the left.

You cannot currently create an overall chord symbol appearance that will automatically be applied to all roots. There is some more detailed discussion of what is possible in the thread I’ve linked to above.