alter user pguser with password 'new password';

[postgres@postgres_vm ~]$ psql
psql (12.4)
Type "help" for help.
postgres=# show password_encryption ;
 password_encryption
---------------------
 md5
(1 row)
postgres=# select * from pg_authid where rolname='hr';
 oid | rolname | rolsuper | rolinherit | rolcreaterole | rolcreatedb | rolcanlogin | rolreplication | rolbypassrls | rolconnlimit |       r
olpassword       | rolvaliduntil
-------+---------+----------+------------+---------------+-------------+-------------+----------------+--------------+--------------+--------------
-----------------------+---------------
 16386 | hr   | f    | t     | f       | f      | t      | f       | f      |      -1 | md566ad2e6b6f
adaa9fd11bfcab906e84c8 |
(1 row)
postgres=# set password_encryption to "scram-sha-256";
SET
postgres=# select * from pg_authid where rolname='hr';
 oid | rolname | rolsuper | rolinherit | rolcreaterole | rolcreatedb | rolcanlogin | rolreplication | rolbypassrls | rolconnlimit |       r
olpassword       | rolvaliduntil
-------+---------+----------+------------+---------------+-------------+-------------+----------------+--------------+--------------+--------------
-----------------------+---------------
 16386 | hr   | f    | t     | f       | f      | t      | f       | f      |      -1 | md566ad2e6b6f
adaa9fd11bfcab906e84c8 |
(1 row)
postgres=# alter user hr with password 'Abcd1234';
ALTER ROLE
postgres=# select * from pg_authid where rolname='hr';
 oid | rolname | rolsuper | rolinherit | rolcreaterole | rolcreatedb | rolcanlogin | rolreplication | rolbypassrls | rolconnlimit |
                        rolpassword                               | rolvaliduntil
-------+---------+----------+------------+---------------+-------------+-------------+----------------+--------------+--------------+--------------
-------------------------------------------------------------------------------------------------------------------------+---------------
 16386 | hr   | f    | t     | f       | f      | t      | f       | f      |      -1 | SCRAM-SHA-256
$4096:dF5WnZnKGXen0mtqZeWldA==$2K8sshkEarHox93X5hmIjKSPxHecXDkjZ56erjIf+dU=:FBbY3+22nVXF83LbfK6DHBK2QpakJA/0RRI3oXs4cdI= |
(1 row)
postgres=#