If your phone is running
6.0 Marshmallow out of the box, you won't be able to customize the Quick Settings panel as the phone is using native
's Quick Settings which doesn't allow this. You will need to update the phone to
7.0 Nougat or later—if the update is available—to be able to customize the Quick Settings panel.
However, if your HTC phone is running
Android 5.0 Lollipop and you update it to
Android 6.0 Marshmallow, you can still customize the Quick Settings panel as the HTC phone will retain HTC's Quick Settings which allows customization.
To check the
Android version of the phone:
Do one of the following: