Stop the array, unassign parity2, as it's not valid after moving slot assignments.
Start the array without parity2 to commit the change.
Stop the array, set a new config, keep all. Go to the main page, do all your rearranging, keep parity 2 unassigned for now. Mark parity as valid.
Start the array, let the parity check complete, it should show zero errors.
Stop the array, assign parity 2, start and let it build.