pg_stat_reset_single_table_counters/pg_stat_reset_single_function_counters only update pg_stat_database column stats_reset. stat_reset shuld update when all the column is reset.
pg_stat_reset_single_table_counters resets the stats of a single table. From your example, it resets the following stats:
select * from pg_stat_all_tables where relid='lzzhang_tab'::regclass::oid;
