Learn about how to lock applications in the background.
Applicable for all ColorOs versions. Check your ColorOS version in [Settings] > [About phone].
Lock the applications in the background.
For ColorOs 5.2.: 1. Press the Menu button.
2. Slide down the application interface until you see a lock icon at the left upper corner. If the icon is grayed out on a certain app, it means it is unable to locked it on the background.
* Pictures, settings and paths might differ from those of your phone, but that do not affect the description in this article.