The new features in Apple's newest operating system allows users to save more battery life, but one could end up draining your wallet. 

The culprit is a little talked-about feature called "WiFi assist," which will switch your phone from a WiFi connection to cellular data if it senses the WiFi signal is unreliable.

This setting is on by default, and could lead to some costly data overages.

Luckily, it is a very easy fix to shut this feature off, as outlined by a Money Magazine. 

To turn "WiFi assist" off:

  1. Open your "Settings" app.
  2. Click on the "Cellular" tab.
  3. Scroll all the way down, there you will find "WiFi assist" and a "toggle switch."
  4. Toggle the setting on or off.