I train dogs not to bark because I just don't tolerate barking. I tell them to stop every time. I haven't seen it fail to work. My official command is a very professional word...."Shut up!".....
I tell people they should use "no bark!" but in real life, most dogs respond best to "Shaddup!".....remember I worked in a couple boarding kennels and that seems to be the universal command.
The barking one might need exercise already. You'd think a "break" would be in order, but the poor thing is just trying to call you back and make sure his good person doesn't get away. This might be why he was dumped, someone thought he was too noisy. I always look at a dog's time with me as a "teaching" time in their life when they get some training and instruction on how to be a good dog, because if someone threw them away, they probably never bothered to teach them anything. You might be the first person to try to get the dog to be quiet.
Try to give it attention when it is NOT barking and don't give it anything it wants when it does bark.
Have you given them names yet? Sometimes dogs will come to names ending in the letter Y because it is common to name dogs those names, they may already have sounds they respond to. Buddy, Sadie, Murphy, Annie, Max, Lucky, Mocha, Harry and Haley are common dog names right now, you might see if any of those work, or just start calling them a name you like. Our dog Bandit was a stray and must have had some other name, but she certainly knows she is "Bandit" now.