Fine customization of a hearing aid to the individual hearing environments and habits of a user are to be simplified and improved. To this end, when the hearing aid is turned on or when the hearing aid is switched to a particular operating mode, neither the value most recently valid for the parameter prior to turning off or switching to a different operating mode nor the parameter value transferred to the hearing aid at the beginning of programming is set. Rather, from the changes to the value of the parameter taking place during operation of the hearing aid a new start value is ascertained and stored, which value is then set automatically after turning on or switching mode.