• By default, that user is internal to your PostgreSQL instance and has nothing to do with any OS X user. For psql, you need #2. Immediately after installation, there should be a user named 'postgres' with no password that has full administrative privileges - try logging in with those credentials (and change the password to something secure ASAP).
• Logging in with username and password: Type your account username in the Name field and press Tab. Then type your password and press Return (or click the Log In button). Auto Login: With Auto Login set, Mac OS X automatically logs in the specified account when you reboot. In effect, you never see the login screen unless you click Log Out from.

The name of your macOS user account and the name of your home folder must both be the same. Changing these names does not change or reset the password of your user account.

Because doing this incorrectly could damage your account and prevent you from logging in, you should back up your important data before proceeding.

First rename the home folder

When you change the password, you'll see a prompt letting you know a new login keychain - what MacOS uses to store your passwords will be created, but your old keychain will remain saved on your Mac. Typically, this means pressing down and holding down the reset button on your router for ten seconds. Afterwards it will be accessible by the default username and password provided below. Once you login with the steps detailed above, you are will be able to alter the username and password as you see fit. Having no password on the OS level effectively means that ssh is disabled for that user. The protocol insists on a non-zero password and thus the hashes of whatever password is supplied fails to match the absence of a hash.

1. Log out of the account you're renaming, then log in to a different administrator account. (If you don't have another administrator account, you can create one in Users & Groups preferences.)
   
2. Open the Users folder on the startup disk. It contains the home folder for each user. To get there, you can choose Go > Go to Folder from the menu bar, then enter /Users.
3. Rename the user's home folder without using any spaces in the new name. You'll be prompted to enter the administrator name and password that you used to log in. If you're using file sharing to share the home folder, you won't be able to rename it until you stop sharing the folder.

Then rename the account

Username And Password Games

While still logged out of the account you're renaming, follow these additional steps:

Default Username And Password For Comcast

1. Choose Apple () menu > System Preferences, then click Users & Groups.
2. Click , then enter the administrator name and password that you used to log in.
3. From the list of users on the left, Control-click the user you're renaming, then choose Advanced Options.
4. Change the “Account name” field to match the new name of the home folder. It should have no spaces.
   
5. The account name also appears in the “Home directory” field, after /Users/. Change that account name to match the new name of the home folder.
6. If you want to change the full name associated with your account, update the ”Full name” field as well. It can be any name, and you can use either the full name or the account name to log in to your Mac or make changes that require your name and password.
7. Click OK, then restart your Mac.
8. Log in to the renamed account, then verify that your old files and folders are visible and the account is working as expected.