Click on the plus sign and select Create project portfolio. After that, tick all the projects you want to view in one place and click on Create project portfolio at the bottom of the list of all projects.
A portfolio with a set of selected projects will be saved in All projects. When you open it, you will see that all the projects are displayed in chronological order in accordance with their start date.
To have a detailed view or a general overview of the progress of all the projects, use the Expand all or Collapse all options correspondingly.