select
      extract( day from snap_interval) *24*60+
      extract( hour from snap_interval) *60+
      extract( minute from snap_interval ) "Snapshot Interval",
      extract( day from retention) *24*60+
      extract( hour from retention) *60+
      extract( minute from retention ) "Retention Interval"
from dba_hist_wr_control
/

Modify snapshot settings

exec dbms_workload_repository.modify_snapshot_settings (retention => 30*24*60);