Default password for postgreSQL
Solution 1:
There is no default password on Windows - the install will ask you during the wizard to create one. If you forgot or don't remember you can:
Go to Control Panel -> Administrative Tools -> Computer Management. There under "Local Users and Groups" you can see all users created for your system. Remove "postgres" and reinstall PostgreSQL
Solution 2:
Though it's late, putting it across:
By Default, the user is 'postgres' and the password is the one which you enter while installing the database. (Version 11,12 I have tested).
Issuing the command:
psql
from cmd in windows will ask for the password of User (Logged in) which might not be available. So you can try login with postgres user:
psql -U postgres
and enter the password used while installing.
Or create a user with login permissions using PgAdmin
tool.
Solution 3:
On a default Windows installation you must specify a database name and you have the option to change the hostname, the username, and the password.
Defaults are: Host name : localhost, Database name : <wasyourchoice>, User name : openpg, Password : openpgpwd