How to establish a geofence around my home for homekit automation

When leaving and arriving home, I have automations set up in homekit. But, I can't adjust how far away from home those automations will be initiated because there is no geofence around "home"--just a pin. And if I enter the address instead of "home" for the location, it allows a geofence which can be adjusted and stays until I click on "done"--then when I come back to the location for the automation, "home" is back as the default along with the pin. Is there anything I can do to alter this?

Thanks.