I have installed the pg_stat_statements extension, but still 'Query stats, etc ' in #PgHero.
This is in postgresql.conf:
shared_preload_libraries = 'pg_stat_statements'
track_activity_query_size = 2048
g_stat_statements.track = all
And I did as postgres user in psql:
CREATE extension pg_stat_statements;
SELECT * FROM pg_available_extension_versions;
...tells me it is installed.