ecobee devices will update themselves automatically, provided they are connected to Wi-Fi. When a firmware version is ready for the public, it will be pushed out gradually over a period of time to all applicable ecobee devices. If your ecobee device is not running on its latest firmware version (listed below), please be patient—your ecobee will update itself as the upgrade continues to roll out.
You can find the firmware version of your ecobee thermostat by going to MAIN MENU > ABOUT, through the thermostat interface.
Most recent firmware versions as of August 1, 2018: