For added security when logging in to your account you can use two-factor authentication in your Grow account.
To activate it, each user needs to go to their own user settings by clicking on their profile image at the top right and selecting "My Account." At the bottom, check the box labeled "Two-Factor Authentication." A text field will appear where they can enter a mobile number. Then click "save" to keep the settings.
The next time that user logs in to Grow they will receive a code via text to enter and complete their login.