Controlling the font size of programs with windows 8.1

Hello,
I have a HP laptop with Windows 8.1 and, I cannot control the font sizes when I use Microsoft programs such as Word, Excel and PowerPoint and internet browsers like Internet Explorer and Google Chrome. What happens is the font sizes get bigger or smaller when I scroll up or down or left and right. Is this a Windows 8.1 issue? How can I freeze the font sizes manually on these programs?
Thanks in advance!
