As I describe in the Youtube video below, many beginners or ones who have just bought a new computer based radio that can do many of the nice features that really improve flying, don't fully understand what those features do or how to set them up. I have talked to a lot of beginners at the field who don't understand the switch positions on their Spektrum radios and how those translate to their D/R and Expo settings in the radio. I have seen ones who swear their radio is resetting their Expo settings that they had setup on a previous flight and then all of the sudden their settings are gone.
What many beginners don't realize is that when they put their radio in the bad or carry case, they are hitting the switch position and setting the position to a new setting. Not knowing these settings don't carry from switch position to switch position, they have in effect "reset" their D/R and Expo settings without even knowing it. This could run into a potentially dangerous situation if a person is not used to flying their plane without Expo and then all of the sudden it has no exponential on the throws and it is behaving much different than they are used to it behaving in the air. As you can understand, this can lead to the person over correcting or over controlling their plane into the ground.
What I tell beginners is make sure you set your switch positions for Ailerons, rudder, and elevator to position 0 before setting your Expo setting. This way you know which position you are making the changes to. Many sport flyers may not have use for all 3 settings on the radio for different D/R and Expo settings, however, for sure if you are wanting to do any kind of 3D flying, you will most likely want to have all of these settings configured for various types of flying with your 3D plane.
Many pros such as Michael Wargo will tell you they have multiple settings to do different things. The lowest, would be non 3D flying such as pattern flying, then 3D, then the highest setting would be tumbling and other snappy maneuvers. This way the plane handles differently for the same inputs to fit different flying situations, 3D etc. Other even more expensive radios such as the Futaba 18MZ can do even more than the standard Spektrum 3 settings.
So basically, each switch can have its own setting. Paying attention to and understanding how this can affect your flying and paying attention to where the positions of the switches are each time you fly is crucial to becoming a better pilot and truly beginning to understand what your radio can do for you in the air. The truth is, you may not need these settings until your flying advances to each consecutive level, however, even if you don't need all of them, you need to pay attention to how you are setting your radio up and again what position the switches are set to.
Take a look at the Youtube video below where we delve into this in more detail: