I think you mean to say allow more posts in a thread. A thread contains multiple posts. That's usually set in your user preferences, but I don't see it there. Then the request would be to add to user preferences changing how many posts we can view in a thread.
The number of posts in the new posts widget is a global setting - easy to increase for everybody, but not settable on an individual basis.
I bumped it up to 10.
I don't think i've even looked at the latest posts since I found the New Posts button, where you see the 20 newest posts. But I wonder, why would you need to click on a Hamburger? If we can choose, I want to click on a taco.
The number of posts in the new posts widget is a global setting - easy to increase for everybody, but not settable on an individual basis.
I bumped it up to 10.