I have tried all types of ways to teach my chihuahua/Greyhound mix to stop barking. She usually barks when hearing new noises, when someone comes to the door (whether she knows them or not), or following another dog's lead. I have tried expensive bark collars, discipline (holding her and saying know; a small spank on the rear; a verbal no, etc)... Any advice on how I can train her not to bark? My daughter would take her to the office with her so she could join the rest of the pack, but she barks at any new visitor that comes to the office, and so is left on her own all day while I'm at work. I'd love to curb this behavior so she could have more fun!
I had a similar problem with my German Shepherd when we brought her in at 3 months. Actually at first when we got her she would not bark at all for a month but then one day we had some visitors over and she finally started to bark, but after that she would not stop at all whenever anyone came to the house.
We also tried many different things like you but nothing worked. However in the end we realized her barking was only the result of curiosity about the people coming to our house. You would think when a large dog like a German Shepherd is barking at someone it's best to keep it tied or away from the person, but that only makes them bark more and in fact can cause them stress. If you just let them sniff the person and allow them to inquire on their own they are more likely to understand and remain calm. This is also a good way for them to learn how to differentiate between a genuine visitor and say for example an intruder. Dogs in general are inquisitive animals so give them the freedom to do that.
Also, with young dogs and puppies it is likely that when you put them away when someone is over they may feel left out and will bark merely to get your attention. Again letting them out and staying around you will avoid that sort of feeling and they are less likely to bark.
In either case shock collars or just shouting "no" at the dog or even giving them a treat may not help as much as allowing them to be curious and ensuring they don't feel ignored. Of course when you are letting out a dog already barking at a person and bringing it even closer to them may sound counter-intuitive, but put your dog on a leash and allow it to sniff the person and familiarize with them.
Hope this helps.
She could have a bit of anxiety. Have you tried a citronella spray bark collar? They don't hurt the dogs but emit a smell that the dogs do not care for. Another method to stop the barking would be to get her a thundershirt so she feels secure wherever she is. My last recommendation would be to get calming treats from the pet store. They are generally made with natural ingredients to help dogs stay calm. However, this brand linked below doesn't work for all dogs and only works for some. You could also try valerian supplements but be warned, they smell really bad.