Ah, beta feedback! You've sent your book off to betas, waited in nail-biting anticipation, and they've written back and you're sitting here with a heap of feedback from multiple sources, unsure of how to go forward.
This step can be super confusing, because you're likely looking at several bits of conflicting information: some of your betas agree that Chapter 31 is perfect. Some think that's the weakest chapter and you have to fix it! Four people love your main character and six people think he's boring! HOW do you choose who is right and who is wrong about your book?
Well, I have the answer, my dear Dreamers!
They're all right. All of them. They're right when they say it's the best and they're right when they say it didn't work for them.
They're right because reading is subjective, as all art is. It's all right, but that doesn't mean it's right for your purposes. The point of beta feedback, again, is not for people to give you technical advice (although if they do spot a typo, I suggest fixing that. ;D ); it's to get a scope on how your book is affecting people. To see if one scene, one character, one arc is generally a flop, and fixing the things that overall don't fit - not fixing everything that everyone has a problem with.
While it can be super tempting to jump on "fixing" things that don't work for people, bear in mind that even if all your betas love your book, the entire audience in the history of ever will not. And at some point you can't change anything more to suit their opinions, because the book is release and oh NOW you get a one-star review from someone who hates your pacing!
But it's too late. The book is out there in the world.
You can't please everyone then, you can't please everyone now. So, I hear you ask, what to do? What advice do I take and what do I leave?
Two things are very important here: understanding your core and knowing when you know better.
Example:
So let's say Character A's personality rubs a reader the wrong way, but you as the writer have the high-level scope that A has to be a jerk until The Defining Moment when they begin to see the light; you can't really have them be a marshmallow early on, even if they're being a nuisance, because otherwise The Defining Moment has no real value.
But THEN let's say another reader says Character A's personality is fine but they have a hard time with a specific act in a specific scene before The Defining Moment - A does something that makes them feel he's less sympathetic in the long run; well, maybe you want to go back and tweak that scene so A doesn't seem quite so irredeemable before or after The Defining Moment.
Both of these beta readers are right in that they read the story and advised on how it made them feel; but one change here serves the overall story, and one does not.
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As the writer, it is up to you to take all the feedback and define which is which; as I advised a friend recently who was struggling through conflicting beta feedback, it comes down to taking advice that will help hone your vision, not change it entirely.
Betas are readers and they have opinions; if you have twenty betas, you'll mostly likely have twenty different opinions on what works and what doesn't. If ten of them agree something is off, you might want to take a second look at that; but bear in mind that not everyone will ship your endgame pair, not everyone will understand why your character does X, Y and Z. Some people are going to think your book is too slow-moving and others will think it's rushed.
What you are mining beta feedback for is not a way to please everyone; it's for the feedback that will help you hone the idea you walked into this process with in the first place. The helps you chip away more of the marble around your masterpiece. You need to have a clear vision of the story you want to tell so the feedback serves your ultimate goal, rather than your ultimate goal being to serve people.
So, ultimately, how do you approach beta feedback? By remembering the goal you started out with and looking at the places where that goal didn't translate to your readers; then making the changes necessary, not just to make every reader happy, but to make sure you convey the ultimate story you started out to tell.