I have a stressed and nervous cocker. She was extremely anxious when I got her so I spent months training and desensitising her to various things. We still have our issues, but it was very rewarding to see her improve on a lot of things! I worked with a dog trainer for a while so I can really recommend getting tips from a real behaviourist, it is so helpful!
I used adaptil plugin for a long time and found it very helpful. But only as a supplement to training. I believe there are also veterinary diets now that help reduce stress. It's worth a try with adaptil in my opinion
Main thing is making sure you do the correct amount of exercise and activity. Too little will lead to a stressed out dog that entertains themself with barking or other destructive behaviours. But too much is equally as bad since an overstimulated dog will not be able to relax. So that's your basis, figure out a good balance of walks, training, playtime and quiet time. Maybe you allready have this figured out, but I mention it since it is the thing we often forget the importance of
One way to stop barking at specific triggers is to connect them to a more desirable behaviour. One example would be every time the doorbell rings you give the command to go lie down and reward this behaviour. With enough repetition the doorbell will be a signal for going to the designated place and lying down rather than barking at the door. It takes a lot of training, but the thought behind it is that you give the dog an alternative action to do and reward that so it replaces the barking behviour.
If some of the noises are scaring the dog and thats why she is barking, you can desensitise her by using rewards. You can fake a little cough and give her a treat or a cuddle and some praise, preferably before she barks. Repeat it with the cough getting louder and more realistic. When she gets better at not reacting have someone else cough while you reward the dog for not reacting. This method can be used for many triggers if the problem is that they spook her
