You can open a Saved Filter, edit it, and then save a new filter
Click the "pencil" icon on the saved filter card
Add the new criteria you want to add to the filter
(in this case, added "Note")
Click Save and Apply
Make sure you click Save as New Filter and change the Filter Name
If you don't click Save as New Filter, then you are updating (saving over) the existing filter.
Now you have another custom filter