Display sizes

A few months ago I started having a problem with all the ingame hud text being to large and overlapping itself. I posted on the boards about couldn't get it fixed and just started ignoring it. Now I'm having an issue where the login screen and and the pregame window (buy champions check masteries ect not sure of name) are tiny and could fit on my phone easily. Help with either would be appreciated.

I have Lenovo Y50-70 with a NVIDIA Geforce GTX card and intel i7 processor still have windows 8.1. I'm kind of crummy with computers so I will probably struggle answering any further questions if you don't tell me where to find the answer. I got this one because I needed a laptop that could run CAD programs.