Submit a parameter proposal along with an initial deposit. The proposal details must be supplied via a JSON file. For values that contains objects, only non-empty fields will be updated.
Currently parameter changes are evaluated but not validated, so it is very important that any "value" change is valid (ie. correct type and within bounds) for its respective parameter, eg. "MaxValidators" should be an integer and not a decimal.
Proper vetting of a parameter change proposal should prevent this from happening (no deposits should occur during the governance process), but it should be noted regardless.