During the manufacture of a set of non-volatile resistance-switching memory elements, a forming process is performed in which a voltage is applied over forming period until a conductive filament is formed in a resistance-switching layer. A heat source at a temperature of 50° C. to 150° C. is applied to expedite the forming process while reducing the required magnitude of the applied voltage. Manufacturing time and reliability are improved. After the forming process, an expedited training process can be performed in which a fixed number of cycles of voltage pulses are applied without verifying the memory elements. Subsequently, the memory elements are verified by determining their read current in an evaluation. Another fixed number of cycles of voltage pulses is applied without verifying the memory elements, if the memory elements do not pass the evaluation.