You can always trash finder preferences. First, enable view for the user Library. In the Finder menu on top of the screen right-click on Go (or control-click), navigate to Library and open it. In the Preferences folder, locate the file com.apple.finder.plist and drag to the desktop. Log out and then log in back. The file will be re-created. See if this helps. If yes, trash the old preference file. If not, the same way you can trash the trackpad preference file.

Alex
3.1 GHz 13" MacBook Pro 2015, 8 GB RAM, OS 10.11.2, Office 2011, TimeWarner Cable
2.8 GHz Xeon Mac Pro 2010, 16 GB RAM, OS 10.11.2, Office 2011, LAN