@Jackyl
We really like ours & used it a lot but DH bought a Pit Boss & has been using it.
The Masterbuilt is nothing more then a smoker with heating element like your oven. Things will cook the same in it as it does your oven. The only difference is you add some wood chips & has a temperature range of 100° to 275°. You don't have to use the chips if you don't want any of the smoke flavor you get from using them.
If you are making chicken put a digital thermometer in it so you can keep tabs on temp during cooking so you will know when it's ready.
Guess you must have the analog controller since you say low, medium, high. I found this online.
An analog temperature controller has a dial that can be turned to “High, Medium, Low” settings. You can not set a specific temperature with this controller.

If you want to smoke ribs at 225F then you need to dial the controller to somewhere in the Low/Medium range and wait 30 minutes to see where the temperature settles. Then you will need to adjust the dial up or down and wait another 30 minutes and see where you land.
Once you get the temperature exactly where you want it you can take a permanent marker and mark the spot on the controller for next time. Of course, if the weather is different (windy, cold) then you are going to need a different amount of power and will have to go through the whole dance again.