The trouble shooting you performed on the modem is just the power cycle that is not resetting modem. The default Wi-Fi password is not the word password the Wi-Fi security key or the   Wi-Fi password mentioned on the modem label so after resetting modem you can use the default Wi-Fi name and password mentioned on the modem label.

This answer doesn’t help me at all- it only confuses things- here’s the story:

 I did make the mistake of simply disconnecting the SVG2482AC gateway from power and then reconnecting again after at least 15 seconds WITHOUT REMOVING THE COAX CABLE. To perform a reset correctly, REMOVE THE COAX CABLE before doing a reset. Perform the reset by inserting a pen point or straightened paper clip into the “reset” hole on the back of the gateway and hold until all the lamps on the gateway have been extinguished. This should restore the gateway’s Web manager ‘software’ login User Name and Password to “admin” and “password”, respectively. (On first use the gateway requires you to change the default password, “password” to something else - I had forgotten the password i changed the default password to and couldn’t log in to the gateway- that’s what prompted my original question, above.

The confusion comes from the fact that the gateway login’s User Name and Password are DIFFERENT FROM THE WI-FI NETWORK(S)’  USER NAME(S) AND PASSWORD(S). The name and password printed on the side of the gateway have nothing to do with the gateway’s Web manager login- the name (SSID) and password printed on the side of the gateway are the default Wi-Fi network(s)’ ‘user name’ and password (and on my SVG2482AC gateway which supports both 2.4GHz and 5GHz networks, that default’ user name’ and password pair is the default for BOTH networks. 
 

Most articles on the  ‘net aren’t careful to keep the terminology straight- I’m distinguishing the gateway’s Web manager User Name and Password from the network(s)’ User Name(s) and Password(s) - and yes, on my gateway the networks’ User Names and Passwords CAN BE THE SAME, OR DIFFERENT, FOR THE TWO NETWORKS. The default SSID and password printed on the side of the gateway applies to BOTH networks on a new gateway. That SSID and password are what devices connecting to the gateway’s networks use to complete a connection.

So I was able to login to the gateway’s Web manager once I had correctly reset it; that was the solution to my original problem- the reference in the original answer, above, was just a confusing distraction.

Yes, you are right. After reset the modem properly, all the customized settings will be changed to default. 

You can use the default password as password to login the GUI web portal.

Once you logged in, it will prompt you to change it for the security reason, you can customize it as your wish.