BUG #12461: Incorrect PSQL User Login in Windows

The following bug has been logged on the website:

Bug reference: 12461
Logged by: John Reilly
Email address: john(dot)reilly(at)tetraireland(dot)ie
PostgreSQL version: 9.4.0
Operating system: Windows 7
Description:

I did a complete installation from the internet 2 days ago. I first used
pgAdminIII to administer the DB and try out features. I then looked at the
tutorial on this site and found that I needed to use PSQL. Once I tried to
start it, I found that I was being rejected because of invalid Password.
Eventually I realised that the PSQL default USER that was being rejected was
my computer User Name and NOT the ONLY registered user in PostgreSQL (user -
postgres). The documentation is confusing in this area as changes have been
made recently.

I then used the '-U postgres' option and all went OK. This is VERY
confusing and needs to be better documented or simplified.

I now can log in without using a password, because that is the way it was
set up in pgAdminIII which may be unintentional (use of the pgpass.conf file
is shared) - for information only.

PS - don't forget pgAdminIII is now included in the PostgreSQL installer, so
that people may go there first for ease of use initially.