Increasing the size of the fonts on the site
Using Jamroom
CTRL++ will increase the font size shown in your browser.
As will ctrl+(mouse wheel up).
If you want to do it for everyone, then you can change the CSS for your site to make it bigger. Where depends on what your skin has it set to. and whether you want to change it just for the forum, or everywhere.
--edit--
for everywhere, you're probably after:
ACP -> SKINS -> YOUR SKIN -> STYLE -> "style section" (site.css) -> SITE CONTENT -> font-size.
updated by @michael: 10/21/15 09:35:01PM
great to hear its of some use.