Oracle 12c Change system password

I am connected to pdb and getting the error while trying to change the password of system user


PDB1@ORCL> conn system/oracle
ERROR:
ORA-28002: the password will expire within 7 days


Connected.
PDB1@ORCL>


What I did is connected to root container and changed the password there


PDB1@ORCL> alter user SYSTEM identified by oracle;
alter user SYSTEM identified by oracle
*
ERROR at line 1:
ORA-65066: The specified changes must apply to all containers


PDB1@ORCL> alter user SYSTEM identified by oracle container=all;
alter user SYSTEM identified by oracle container=all
*
ERROR at line 1:
ORA-65050: Common DDLs only allowed in CDB$ROOT


PDB1@ORCL> select con_id, dbid, name, open_mode from v$containers;

    CON_ID       DBID NAME                           OPEN_MODE
---------- ---------- ------------------------------ ----------
         3 3345156736 PDB1                           READ WRITE

PDB1@ORCL>

PDB1@ORCL> show con_id

CON_ID
------------------------------
3
PDB1@ORCL>

PDB1@ORCL> alter session set container=CDB$ROOT;

Session altered.

PDB1@ORCL> show con_id

CON_ID
------------------------------
1

PDB1@ORCL> alter user SYSTEM identified by oracle container=all;

User altered.

PDB1@ORCL> alter session set container=pdb1;

Session altered.

PDB1@ORCL> show con_id

CON_ID
------------------------------
3
PDB1@ORCL> conn system/oracle
Connected.
PDB1@ORCL>