I downloaded Kubuntu from a USB drive, but everything on the desktop was too small to read. I did manage to do the preliminaries with the aid of a magnifying glass, but there's no way I can continue using Kubuntu with this problem. I'm using a Lenovo Yoga 3 Pro Ultrabook. I would appreciate any suggestions to help me get started with this intriguing system. Thanks.

I suppose the resolution isn't set correctly. Try going to System Settings>Display and Monitor. Click the screen you're using and set the expected resolution from the slider there.