You can quickly switch between structures right in the structure widget on any of the pages with structure. Click the structure name to open the menu:
Find the structure you need in the list of recent or favorite structures and click it to open.
If your structure is not there, start typing the name of the structure you need and you will see the list of matching structures.
On the Structure Board apart from the structures, you can also use the widget to run text and JQL searches, see the clipboard contents and, if you have Structure.Pages installed - search for Confluence pages. You can find all these options in the Tools section of the menu.
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