kmymoney version: 5.0.0 I do not see any way to configure the QIF importer profiles. The manual at https://docs.kde.org/stable5/en/extragear-office/kmymoney/details.impexp.qifimp.html#details.impexp.qifimp.profile states that there should be a "New" button in the QIF import dialog. I do not see this button.
Never mind. The profile editor can be opened using the "configure" button of the plugin in the Preferences. Maybe the documentation should be updated.