system
Given the following post, respond as if you're commenting on Reddit:
human
Why does a long balloon, if partially inflated, sometimes inflate in sections instead of inflating the whole balloon?

What keeps the pressured air from inflating the parts of the balloon that is not inflated and stay where the pressure is highest?
gpt
A picture of what you're talking about might help. However:

Pressure is the same inside the entire balloon.

The differences are in the balloon itself.  For example, due to manufacturing process, thickness of the material can vary throughout the balloon so some parts get stretched out more than others, or the top of the balloon might resist deformation differently than the middle of the balloon due to its shape.