Save the before-and-after record
Note the Nest model, installation date, room and target temperatures, outdoor conditions, and AUX or emergency indications. Keep usage history and bills from before and after.
Distinguish the indoor fan, outdoor compressor, and backup heat. Ask whether the thermostat history identifies them reliably or whether approved monitoring is needed.
Do not rewire the thermostat, change installer menus, or disable backup heat based on another household's settings.
Verify the configuration
Ask a qualified provider to confirm compatibility, wiring, equipment identification, and the tested heating sequence. Commissioning is that post-installation check that the system operates as intended.
Google explains that Heat Pump Balance applies to supported heat-pump systems with auxiliary heat and affects when it is used. Dual-fuel systems use a different arrangement and do not use that feature. This is a reason to verify your system rather than copy a setting. Google Heat Pump Balance guidance.
Ask the provider to explain the owner settings and what they change. Proper setup must maintain needed heat, not merely prevent an AUX message.
Investigate the bill separately
Compare energy used, billing days, weather, schedule, and current rates. If gas heating was replaced, include gas as well as electricity. A larger electric bill alone does not show the total heating-cost change.
Ask whether backup operation is expected for the conditions or reflects a setup or equipment problem. Poor comfort also calls for equipment and airflow checks.
Your next step is a control-verification visit with usage and bill records attached. Request an explanation connecting the settings, confirmed heat-source operation, and household costs. Make changes from those findings and retain the correction record.