How can I modify the number of "Most recent documents" that Windows displays on the Start menu?

Start a registry editor (e.g., regedit.exe).

Navigate to HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionPoliciesExplorer.

From the Edit menu, select New - DWORD value.

Enter a name of MaxRecentDocs, and press Enter.

Double-click the new value, and set the base to Decimal.

Set this value to the number of documents that you want Windows to display (in multiples of 15), and click OK.

Close the registry editor.