From the Zappiti's main menu, select the icon "settings".
Go in Apps, then choose the app concerned (Zappiti, Zappiti Explorer or Zappiti Music).
Then select "Storage".
The next screen contains two buttons : "Clear Data" and "Clear cache" (becarefull, they are almost invisible)
Use the "mouse" function to click on these two buttons
Once it will be done, your preferences should be reseted.