This information applies only to those users who connected their WWN and Flair accounts prior to August 31, 2019. For more information, see our article on how Flair works with Nest after the Google transition.
You can also change your Nest thermostat mode by clicking on the Mode button in the top right and selecting Heat, Cool, or Heat/Cool:
If you make this change while your Nest is in Away mode, you will be prompted to switch from Away to Home. Once you click "Yes" to switch from Away to Home, the Flair app will switch the Nest mode state: