While the Global Search's "Quick View" (Dropdown) provides search results that the system determines are likely the most relevant. Often, users need more search options. In this case, click on the "View All Results" (Link) at the bottom of Quick View.

Clicking the "View All Results" (Link) at the bottom of the Quick View (Dropdown) closes Quick View and opens Advanced Global Search. 

Screenshot of the “Advanced Global Search” (Screen) with red highlighting of the two parts.

When you expand a left-side section and select a filter within that section, the other sections hide.

To return to the initial stage where all sections are displayed, uncheck the filters, or, click on the Documents (Section).