If you change a Filter the display in the Content Browser adapts directly, any bookmarks referencing this Filter may break.
Filters require values in fields, that must have "Include in filters" configured. However, you cannot add a relationship, fieldset, or geo point fields directly to the Channel or List Filters. You can add the fields used in the underlying relationship or fieldset if it is not one of the non-supported fields.
If you change a Query Filter used in a Tagbox, which prevents previously applied tags from being used, the tags will stay assigned on Content Items until those items are edited. They cannot be assigned new.