RecruitingBehavioural interventionExecutive Function Training for Children and AdolescentsThe goal of this clinical trial is to evaluate how different approaches to executive function (like adding game-like features, varying the number of tasks, and providing coaching) can enhance executive function outcomes in adolescents with and without ADHD. The main questions it aims to answer are: * What components of executive function training contribute most to improving outcomes? * How do training components vary in their impacts on adolescents diagnosed with ADHD compared to those without a diagnosis? * What individual characteristics influence the effectiveness of executive function training? Researchers will test six different training setups to examine which setups are the most effective for different people. They will evaluate both how well participants follow the training schedule and whether there are changes in psychological and cognitive outcomes after training. Participants will complete: * 40 training sessions over 4 weeks * A set of tests and surveys before and after the training * Follow-up assessments and surveys 6 months after finishing the training