On the menu in the top right corner of the screen, you will find a heart-shaped icon. By clicking on the arrow next to it, you will see all tasks you have marked as favourites.

To mark a task as a favourite, once you are in the task screen, you will see another heart-shaped icon on the right-hand side, but greyed out. By clicking on it, it will turn dark blue, indicating you have successfully marked that task as a favourite. You can easily access it next time by selecting it from the Favourites list, which can be found either in the top right menu or the middle right menu under the Favourites column.