HTC One M8 - Manual (Page 123)

§ Moving apps to the storage card doesn't back up the apps. If you do a factory
reset, your phone loses the apps. You'll need to reinstall them.
§ When you remove the storage card and insert it in another phone, the apps on the
storage card won't be installed automatically to the other phone. You'll need to
reinstall them.
About storage encryption
On the phone storage, you can encrypt data such as your accounts, settings,
downloaded apps and their data, media, and other files. On a storage card, you can
only encrypt files.
Set a lock screen PIN or password before you start encryption. Fully charge the
battery first, or keep HTC One connected to the power adapter during encryption.
This process may take about an hour or so.
You cannot undo encryption on the phone storage. If you want to return to an
unencrypted phone, you must perform a factory reset.
Once you enable storage card encryption, only new files added after encryption will
be encrypted. Files already on the card will not be encrypted. Also, storage card
encryption doesn't reformat or erase your card. Encrypted files on the storage card
can only be opened by the phone that encrypted them.
How to encrypt
1. Go to Settings, and then tap Storage.
2. Tap Phone storage encryption. Or, tap Encrypt SD card content.
3. Tap Next.
4. Enter the lock screen PIN or password, and tap Next.
5. Tap Enable encryption.
During phone storage encryption, the phone may restart a few times. When storage
encryption is complete, enter your PIN or password.
If you turn off SD card encryption to stop encrypting new files, previously
encrypted files will remain encrypted. To access these files, you must enable
encryption again for your storage card.
Google Drive
Using Google Drive on HTC One
Store your photos, documents, and other files on Google Drive to access them on
HTC One, your computer, and your other mobile devices.
On HTC One, just use your Google Account to sign in to your Google Drive storage.
You can then:
123 Storage