Last Updated: Mar 21, 2014
How does my HTC One M8 back up and restore contacts with Gmail™?
If you sign into a Google™ account during the initial setup process, your HTC One M8 automatically synchronizes contacts with your Gmail account.
If you add contacts to your HTC One M8 before signing into your Google account, your contacts don't synchronize with Gmail. They save as Phone Only contacts.
After you've associated your Google account with your HTC One M8, anytime you add, import, or transfer a contact, your device prompts you to choose where to save the contact. Contacts don't synchronize with your Google account unless you select Google Account.