There are two ways of doing this.
OPTION 1 - USER SIDE:
The user can choose per website, to increase or decrease the website ZOOM LEVEL by going in to their browser's menu and click on the [-] or [+] which are are on either side of the "100%" shown. This will SHRINK or ZOOM the website they are currently connected to. This is the most commonly accepted way of changing the website size today.
CHROME:
https://support.google.com/chrome/answer/96810?hl=enFIREFOX:
https://support.mozilla.org/en-US/kb/font-size-and-zoom-increase-size-of-web-pagesINTERNET EXPLORER:
http://windows.microsoft.com/en-us/windows/zoom-webpage#1TC=windows-7or
OPTION 2 - SERVER SIDE:
Control Panel > Styles > [SELECT YOUR STYLE] > EDIT
Find the font items you want to increase the size of for everybody on your site. Increase their "font-size:" numbers from "12px;" to "14px;" or by a factor of 2 or 3. Whatever you feel comfortable with. You must do this to all elements that you want to change the font size to. This may take a bit of trial and error to find exactly the combination that looks good and works well on your website design. The two main items you would be looking for, are "body" in General, and "post_inner" in Post Properties.
OPTION 1 - USER SIDE is the preferred method.
