In addition to the fields you can search from the dropdown option in Mendeley Desktop, you can also search by tag. Simply type Tag:copyright, Tag:"information literacy" (put phrases in quotes), or Tag:[your tag] in the search box:
Your results will show in a single folder that you search or in the All Documents folder:
Using the File Organizer, drag and drop the fields you want to appear in your Mendeley Desktop document files. I use Author and Year, but you may wish to also use the Title or the Journal. If you have multiple files by the same author in the same year, Mendeley will automatically number your files instead of overwriting them. If you do not like the hypen-separated default in your file names, check out the options on the dropdown menu on the right and see my example of underscore-separated file name structure in the Windows image below. The other options are comma or period separated values. You can also sort the folder's contents into subfolders. See the Windows image below.
From the Mendeley Desktop menu, click on Preferences > File Organizer.
On a Windows computer, click Tools > Options > File Organizer.