Background To decide what programming parameters to use for cochlear implants (CIs) in partial deaf patients can be challenging. Objective The processor programming form, categorised as electrical complement (EC), electro-acoustic-stimulation (EAS) or electric stimulation (ES), and difficulties switching programming form were investigated. Methods A retrospective investigation of medical records and audiograms was conducted in adult patients intended for EC and EAS. Results Eighty-four ears (80 patients) were included. Twenty ears were initially fitted with EC, 32 with EAS, 30 with ES and 2 with both EC and EAS. Sixty-four ears met the criteria to use EC or EAS at initial fitting, however only 54 ears were fitted with EC or EAS initially. Twenty-eight patients altered between at least two programming forms and six of those experienced difficulties to adapt to a new form when their low-frequency hearing deteriorated. Twenty-five percent of patients initially fitted with EC or EAS switched programming form within two years. Discussion Further studies on how to choose the most beneficial sound processor programming parameters for EC and EAS, and when to change between programming forms, are warranted as well as clear guidance on choosing the right candidates for EC and EAS.