First of all, never reward the noise with allowing her to have what she wants. MARK her silence with a marker word and food. I use YES (it is short and effective) and immediately give food. DON'T take her to meet ever Tom Dick and Harry on the street. This can lead to reactivity if she meets the wrong person or the wrong dog. Put a collar on her, not a harness and shorten your leash to about 2 feet and keep her next to you. Do not have people approach her and do not allow her to approach. Have her sit. Reward with food both sitting and silence. KEEP QUIET. One command cue. I pull my dog off to the side and have him sit with his focus on me while people go by.
Training may be going well, but clearly she won't sit and remain sitting when something exciting is going on. So you need to train that and then you need to proof it and make sitting VALUABLE TO THE DOG. This means the REWARD for sitting needs to be better than a pat on the head or a piece of some dog kibble treat. Get something REALLY good like bits of hot dog or pieces of cheese (small pieces the size of a pinky fingernail work as good as big pieces). Proof the sit in the house, in the yard (front and back), in the basement, on the sidewalk.. Dogs do not generalize behavior between locations until you have taught them the behavior in about 20 different locations. So, sit in the house is not understood as sit in the yard or out on a walk. You have to train it. You have to train the dog to focus on you and you need to make focus on you valuable to the dog.
Have a crate. When guests come over, crate her OUT OF SIGHT or the activity. It is the best thing going forward. The dog has NO need to be part of guests and company. If someone comes to the door unexpectedly, tell them to please wait before coming in, you have to put the dog up. Having a friendly dog is great but having a dog that ignores you in preference for new people is not so great. So eliminate the problem by putting the dog up.
Make the dog's time with you interesting and fun for the dog so she prefers time with you and not everyone else.
Be calm. YOU be silent. When the Dog is silent reward it calmly.. whining is a waiting game. You have to be patient. Any silence is rewarded. Calm is rewarded.
Punishment in a whining dog often makes it worse.