need to audit changes to function/procedure/package/triggers

Hi, we use oracle database 19c and we need audit all changes to function/procedure/package/triggers by all users.   

I have created the following procedure for testing the audit: 

---------------

drop procedure my_proc_test1;

CREATE OR REPLACE PROCEDURE my_proc_test1

IS

  i  NUMBER;

BEGIN

  i := i + 1;

END;

----------------

I tried enabling audit by:  

(audit_trail=DB, EXTENDED)

AUDIT DROP ANY PROCEDURE;

AUDIT ALTER ANY PROCEDURE;

AUDIT EXECUTE ANY PROCEDURE;

and 

AUDIT DROP ANY PROCEDURE BY ACCESS;

AUDIT ALTER ANY PROCEDURE BY ACCESS;

AUDIT EXECUTE ANY PROCEDURE BY ACCESS;

but when I try recreating the procedure by re-running "CREATE OR REPLACE PROCEDURE my_proc_test1" statement, nothing shows up in audit trail tables: sys.aud$, dba_audit_trail and DBA_AUDIT_TRAIL.