On the Q&A homepage you will see a panel of tiles, one for each chapter.
Click on the chapter heading to view the sections in that chapter.
Click on a section to reveal all subsections within that section.
Click on the subsection: there may be further subsections or, alternatively, questions, within a subsection.
Once you have revealed the questions within a subsection, click on a question to expand all questions within that subsection. Click on the question again to close all questions within that subsection.
To close a chapter, section or subsection, just click on it.
You can also navigate using the Navigation Panel.