Welcome to the forum!
Do you want to make something like the logo with stars, on the linked page?
To answer your question directly, you can't adjust the polar grid after it's created. But if you check the Live Preview box at the bottom of the dialog, you can experiment with different values for all the variables in a live way. Note that for a very large grid, the live updates might take a few seconds to display. (grids can become very heavy fairly quickly - but on a computer that's not too old, it should be ok)
For creating the stars (although I realize I'm guessing that's what you want to do), I don't know any way to make them look like they are stretched over polar grid surface. I mean like if you wanted to draw a regular star and then stretch it into that appearance - I don't think Inkscape can do that. It seems like I heard that some raster graphics programs can do that, but I'm not sure which one.
So for the stars, I think you'd have to either auto-trace or manually trace the raster image.
Maybe you have something else in mind. But I thought I'd mention it, just in case.