1.  Slide to 3rd page;

2. Tap "Icon Disguise" feature

3. According to hits to have a try: long press the logo;

4. Enable now.

The icon will be changed in a few seconds or you can reboot phone to refresh icon. After Icon Disguise is enabled, you can long press Calculator logo to open GalleryVault. 

There are two methods to launch after disguise icon:

Basic Open Method: Long press the Logo on the top left;

Advanced Open Method: Input Password and double press "=". For example, Your password is "1234", you enter "1234==" to open the Calculator.