Postgres - returning custom values ie. "true" rather than "t"
You can use a CASE WHEN clause to custom the output :

SELECT CASE WHEN status THEN 'true' 
            WHEN NOT status THEN 'false' 
            ELSE 'uknknown' 
       END AS status 
FROM mytable;


If you want to change the default output of PostgreSQL in order to output 'true' instead of 't', I'm pretty sure it is not possible.