Dice Roller Defaults
The button only exists for the GM, but it lets them have things like Reroll Max, or a system selection, pre-set for the players... but the players can still undo it all for specific die rolls when they need to. I don't know how hard it would be to make it so a GM could set it up differently for different players, but I'm not sure how generally useful it would be, either.
I have no idea what you're trying to do, but... these get kind of complicated, but you can set up the Dice Roller Links, and those have a whole lot of settings. If you look in the FAQ under General RPoL Information, RuBB Code Tips and Tricks, there's "How do I... put die roller links in posts and character sheets?" And that has a list of all the different options, and they do cover.. at least almost everything you can set in the Configure the Dice Roller thing.
So if you wanted an individual DR configuration for different players, you could probably set those up in their character sheets, and that might do... whatever it is you're hoping for.