bsk_pdfm_filter_date_filter_text_day
Default option null text for day dropdown is Day, you may use this filter to update it.
Example
/** * Change the default option null text of day dropdown in date filter * @return new option null text */ add_filter( "bsk_pdfm_filter_date_filter_text_day", "change_date_filter_day_text" ); function change_date_filter_day_text() { return 'Reset Day to filter PDFs'; }