I'm not sure what greyed-out settings you are referring to. But to increase the number of fragments that are created during collisions and also increase the amount that are automatically transitioned to full simulated bodies, click Home > Settings > General, then expand Simulation Performance. Here you can manually set the amounts for Max Attracting and Max Non-Attracting. This should help! You can also turn off Dynamic Budget in Home > Settings > Performance if it looks like too many of those are being removed.