@Re-searcher:
I do not know, what you are complaining about:
The settings does exactly, what it is made for: "Set the grid-dot-size to the value in the spinbox"
It looks like you chose a setting of "5" for the screenshots you made.
When I look at your screenshots, all grid-dots in both screenshots have the same height and width of 5x5.
And as written before:
The size of the grid-points does not change with zoom-factor in QET!
In relation the points look smaller, when zooming in a design.
But that's just an optical illusion:
Use a graphic-software to check the size in both screenshots!
You will see, that all points have the same size of "5x5" in your screenshots.
In the attachment you see both of your screenshots zoomed to 1200% with GIMP (no shouting here: it spells with capital letters).
I marked the diagonal of your black dots with red pixels, so you can count: 5 in each of your screenshots.