Changing the passphrase of the Persistent Storage
To change the passphrase of your Persistent Storage:
- Choose Applications ▸ Tails ▸ Persistent Storage to open the Persistent Storage settings. 
- Click on the Change Passphrase button on the left of the title bar. 
- Enter the current passphrase in the Current Passphrase text box. 
- Enter your new passphrase in the New Passphrase text box. - It is impossible to recover your passphrase if you forget it! - To help you remember your passphrase, you can write it on a piece of paper, store it in your wallet for a few days, and destroy it once you know it well. 
- Enter your new passphrase again in the Confirm New Passphrase text box. 
- Click Change. 
You can now restart Tails and try to unlock the Persistent Storage with the new passphrase.