If searching your Mac doesn’t return expected results (for example searching in Outlook), rebuilding the Spotlight index might help.
Choose Apple menu (apple icon in the top left) > System Preferences, then click Spotlight
Click the Privacy tab
This shows a list of locations that Spotlight is prevented from searching - click the Add (+) button and select the folder or disk, or drag the folder or disk that you want to index again
Once it is added, select the folder or disk and click the Remove (--) button to remove it from the list.
Quit System Preferences. Spotlight will re-index the contents of the folder or disk.