Default [Q] Why do my apps still saved to my SD card?

Hi,

I'm running an Alcatel One Touch Mini with Jellybean. I have over 1gb of internal storage space not in use and have the option checked for apps to save to the internal storage, however, apps such as whatsapp still seem to save data on my SD card.

Why is this, and how do I rectify it? I prefer the space on my SD card to be saved for music.

Thanks