You can follow below simple steps to edit the saved search.
Open your Saved Searches on the Dashboard from the Homepage under 'Products > More Productivity Tools > Saved Searches'
Click on the desired Saved Search.
In the search query page, update the query as per your desired changes and click on "Save & Set Alert".
In the "Save & Set Alert" window, update the saved search name with the same name used for the saved search under editing. This action will prompt you to update the existing saved search. Click on Update to reflect the changes.