When I upgraded my version of Ubuntu I noticed right away the new scrollbars in my applications. At first, it was kinda cool but after a little while it was not really what I needed.
Here's a quick tip on how to remove the overlay scrollbars in your Ubuntu application
sudo su echo "export LIBOVERLAY_SCROLLBAR=0" > /etc/X11/Xsession.d/80overlayscrollbars
Logout then login
If this solution doesn't work for you, you will need to remove the overlay scrollbars packages.
sudo apt-get remove overlay-scrollbar liboverlay-scrollbar-0.1-0