The County Commissioners may from time to time amend, supplement, change or modify this subchapter. No such amendment, supplement, change or modification shall become effective until such time as a duly advertised public hearing has been held, at which interested parties and citizens have had an opportunity to be heard. Notice shall be given as follows: at least 15 days prior to the date fixed for public hearing, publish a notice containing the amendment, supplement, change or modification to this subchapter; the date, time and placed fixed for the hearing; and the general nature of the hearing in at least 1 newspaper of general circulation in the county.