PgAdmin on Ubuntu 20.04 FATAL: password authentication failed for user - postgresql

Question

I've installed Postgres and PGAdmin4 on Ubuntu 20.04, but I'm not able to create a server and connect to the database
As I have seen in several solutions, I changed the method to md5 on my pg_hba.conf file
# Database administrative login by Unix domain socket
local all postgres md5
# TYPE DATABASE USER ADDRESS METHOD
# "local" is for Unix domain socket connections only
local all all md5
# IPv4 local connections:
host all all 127.0.0.1/32 md5
# IPv6 local connections:
host all all ::1/128 md5
I have as well connected to psql, created new users, alter password and restart the server by running sudo systemctl restart postgresql
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------------------+-----------
postgres | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
Any ideas?

Answer 1

Run the following commands:
sudo -i -u postgres
Input your sudo user password
psql
ALTER USER postgres PASSWORD 'new_password';
\q
exit
Now change config file to use this new password:
sudo subl /etc/postgresql/13/main/pg_hba.conf
(subl means subliime text, you can use any other text editor).
Edit this part of the file: change peer to md5
# Database administrative login by Unix domain socket
local all postgres peer
# "local" is for Unix domain socket connections only
local all all peer
restart the postgres service
Run this command to sign into postgres using the newly created password:
psql -U postgres

Answer 2

sudo -u postgres psql
and set new password
postgres=# \password
Source of solution:
https://www.youtube.com/watch?v=ej08u5xPa64

Answer 3

First we have to get inside postgres by using
sudo -u postgres psql postgres
Enter password for user postgres
Now the terminal will be like this:
postgres=#
Now enter the given line after postgres=#
CREATE USER username WITH PASSWORD 'your password';
(put your password inside quotes('') and don't forget semicolon(;)