The upcoming Ulefone Future model just received another extra function with the System UI Tuner for Android 6.0 Marshmallow, which should allow the users to tweak a bit the UI. Nothing major, but ...

If your Android phone has its own dedicated System UI app, you can clear its cache by following these steps: On your Android device, navigate to the Settings app.

Hidden System UI tuner Customize your Android’s status bar and notifications using the System UI Tuner. Long-press the Settings icon in the Quick Settings menu until it spins.