Settings : Appearances
Inside Appearances, you can choose themes and set up how each tasks are shown. Title and notes can each be set as 'All, 3 Lines, 1 Line' and '3 Lines, 1 Line, None'. Duration, subtasks and notes icon can be toggled to be shown or not as well.
Currently on 3.0, there are 4 themes. GoodTask 3, Dark, GoodTask Classic and White. Each theme works throught the app to give characteristics of each theme. More will be added on later updates.