Each version of the Betaflight Configurator is configured to work with a certain subset of firmware for the flight controller. The Configurator's user interface (UI), options/settings/functions/features available via the UI, ranges, default settings/tuning, and the terminology/nomenclature (even for a feature/function that used to be the exact same function) changes between major releases/versions. There is no 100% backwards compatibility. As such, you MUST use the correct Configurator version for the firmware version on your drone. This simply a necessary evil when enjoying Betaflight's open source application and firmware.
Use Betaflight Configurator 10.4.0 for firmware versions 3.x.x.
Use Betaflight Configurator 10.5.1 for firmware versions 4.0.x.
Use Betaflight Configurator 10.6.0 for firmware versions 4.1.x.