If you're talking about viewing reports in a browser, you can change the font size in the generated reports by editing the dmrpt.css style sheet. You can do that by double-clicking on it and it should open in Notepad.

Here's a typical league webpage under the old style:

http://www.bristolbasebal.../BBL/2010/tm11_tmbat.htm

Here's our tweaked webpage with all font sizes increased a couple of points:

http://www.cfa21.net/2010/tm11_tmbat.html

Much easier to read but not so large as to scream "you're blind!" or take up the whole browser window in most configurations. I forget how much I changed the point sizes but the specs are below:

body {background-color: #ffffff}
h1 { background-color: #ffffff; font-family:Verdana,sans-serif; font-size:16pt; font-weight:bold; }
h2 { background-color: #ffffff; font-family:Verdana,sans-serif; font-size:14pt; font-weight:bold; }
h3 { background-color: #ffffff; font-family:Verdana,sans-serif; font-size:12pt; font-weight:bold; }
h4 { background-color: #ffffff; font-family:Verdana,sans-serif; font-size:11pt; font-weight:bold; }
p.dmrpt { background-color: #ffffff; font-family:Verdana,sans-serif; font-size:10pt; font-weight:bold; }
a.dmrpt { background-color: #ffffff; font-family:Verdana,sans-serif; font-size:10pt; font-weight:bold; }
table.dmrpt { background-color: #ffffff; font-family:Verdana,sans-serif; font-size:10pt;}

tr.dmrptsecttitle { background-color: #B71234; color: white; font-weight: bold; }
tr.dmrptsecthdr { background-color: #BBBBBB; color: #B71234; font-weight: bold; }
tr.dmrptbody { background-color: #ffffff; color: black; }
tr.dmrptbody2 { background-color: #DDDDDD; color: black; }
td.dmrptbodyhdr { background-color: #B71234; color: white; font-weight: bold; }

Hope that helps.