Dog keeps barking at outside noises

[Infinity∞]

I got a pomeranian from a family friend and she's about 2 years old. She isn't spayed.

She barks at most sounds she hears outside when she's inside and every knock or doorbell. We bought a muzzle but she doesn't seem to like having it on.

She also growls at some people during her walks and sometimes stays in one spot shaking when she has her leash on, this includes inside and outside.

The previous owner rarely brought the dog outside.

[Mikey]

Maybe the dog is just not used to outside environment, take her outside more let her run around let the dog be free!

[Feir]

You could try distracting here when she barks or growls, like clap your hands to make a noise that will stop thinking about what is bothering her, this works well unless the clapping scares her and makes her more jumpy.
Maybe try to get her to sit and just stroke her and talk in a calm voice until she feels safe, it's like comforting her but sometimes this can be like you're reassuring her that it's ok to growl or bark.

Try either of those, if one doesn't work then the other should, depends how your dog interprets your actions.

[Ponygon]

It's probably just like that because of the previous owner. Yeah, just take her outside more.

[Dr.Cooper]

It takes time for an animal to adjust in a certain environment.
Like other fellow member said, you can take the dog out and see.

Take good care of them.