Puppy learning bad behaviours from older dog

Hello, my 20 week old vizsla is learning bad habits and I was wondering if anyone could advise me on how to prevent it! My 5 yr old lab is a bit of a barker/growler. He barks in the boot and in the garden if people go past, territorial I suppose? He can be really quite scary in the boot but as soon as the boot is opened he's ok! BUT now my pup has started to copy him and is barking at people i the boot and also barking at our neighbours etc through the fence. Please help me! I don't want two barking dogs terrorising people who come near our car or house! I've never had dogs before who barked at visitors etc.
I have socialised my pup seperate from the lab to try to prevent this in her but I can't keep them seperate all the time! She was barking at people through a fence yesterday for no reason. I am so disappointed that she is behaving this way and not very sure what, if anything, I can do

I would suggest distracting her, and teaching her quiet. As soon as she shuts up barking, say good quiet and use a treat or toy, whichever she is most motivated by, and loads and loads and loads of high pitched praise.