To activate full screen view, simply click the expander icon in the top right corner of the instruction pane of any Activated Checklist. It's the icon that has two arrows pointing away from each other. You can click on the Expander icon when the Activated Checklist in either view or run mode.
This will expand the Activated Checklist to fill the current window. Once the Activated Checklist has been expanded, the steps in the checklist will automatically be synced with the information in the instruction pane.
To shrink the window again, click on the Expander button again.
To expand the window automatically each time, click the checkbox "Always fullscreen". This option is only available when the Activated Checklist is in run mode.