How to enable Global Search
To enable Global Search, follow these steps:
Navigate to Site Configuration → Site Configuration → Portal Page Elements
Click New Element.
From the Type dropdown, select Search.
Enter a Name for the search element.
Click Save Settings to apply your changes.

An image highlighting the creation of a new portal page element for global search
All Portal Page Elements you create appear as a subsection within the configuration menu under the name you assigned. While you cannot delete Portal Page Elements once created, you can make them inactive. To do this, follow these steps:
Click the Edit icon next to the element you want to deactivate.
Click Make Element Inactive on the toolbar.
Inactive elements are listed in a separate tab, where you can edit and sort them on the page just like you do with active elements.
To finalise the configuration of Global Search, follow these steps:
Navigate to Site Configuration → Site Configuration → Portal Page Elements → {Element Name} using the name you provided earlier.
Click Settings next to the Search element.
In the Search Modules section, check the boxes for each module you want to include in Global Search.
Choose whether to Show Users in search results.
In the # of Results per Page field, enter the number of results to display per page in the Search Results window.
Click Save Settings to apply your changes.

An image highlighting the configuration for global search