Modify OWNER on all tables simultaneously in PostgreSQL Database

1) pg_dump -s YOUR_DB | grep -i 'owner to' | \

sed -e 's/OWNER TO .*;/OWNER TO NEW_OWNER;/i' | \

psqL YOUR_DB

2) 

Tables
SELECT 'ALTER TABLE '|| schemaname || '.' || tablename ||' OWNER TO my_new_owner;' FROM pg_tables WHERE NOT schemaname IN ('pg_catalog', 'information_schema') ORDER BY schemaname, tablename;


Sequences

SELECT 'ALTER SEQUENCE '|| sequence_schema || '.' || sequence_name ||' OWNER TO my_new_owner;'
FROM information_schema.sequences WHERE NOT sequence_schema IN ('pg_catalog', 'information_schema')
ORDER BY sequence_schema, sequence_name;

Views
SELECT 'ALTER VIEW '|| table_schema || '.' || table_name ||' OWNER TO my_new_owner;' FROM information_schema.views WHERE NOT table_schema IN ('pg_catalog', 'information_schema') ORDER BY table_schema, table_name;


This generates all the required ALTER TABLE / ALTER SEQUENCE / ALTER VIEW statements, copy these and paste them back into plsql to run them.
Check your work in psql by doing:

\dt *.*
\ds *.*
\dv *.*