postgres is empty after installation on Ubuntu

where do i set my default password?

The way postgres installation for Ubuntu is set, there's no way to explicitly set the password for the default user postgres. You set the password after installation and it involves making changes to the pg_hba.conf file typically located in /etc/postgresql/postgres_version/main.

Find the line with the user postgres and change it from peer to trust eg.

local all postgres trust

Save the file then open a terminal and restart the postgres service by typing sudo systemctl restart postgresql

Then connect using the psql client as user postgres. psql postgres postgres

and alter the user postgres and include a password.

Go back to the pg_hba.conf file and change from trust to md5.

Restart the service again as before and proceed to connect to postgres.