What is your screen resolution?
And you didn't modify any default text or Windows settings in Control Panel\All Control Panel Items\Display?
No, the display was like that when I launched the program for the first time. I tried changing the text size later but that didn't solve anything. Everything is now at its orginal settings. (I'm using windows 8.1 if that makes any difference at all.)
It shouldn't. I run Windows 8.1 on 1600x900. What is your video card and driver? There's no doubt you have some strangeness.
Video cards:
AMD Radeon HD 7560D
AMD Radeon R5 235 + HD 7560 Dual Graphics
Driver:
WDC WD10EZEX-60ZF5A0