A little research resulted in a suggestion to change the Accessibility options. I felt a little resentful at the suggestion my eyesight was in some way to blame but I gave it a try. Here’s what you do:-
Open the CHM file.
-> Options -> Internet Options -> Accessibility -> Ignore Fonts Sizes on specified Web pages
Presto! You can read the help file but don’t get too excited, now go to Internet Explorer and visit your favourite website, what do you see? In most cases it will be a mess with silly font sizes.
I was crushed.
Further research suggests CHM Authors set font sizes but all files were using tiny fonts. Either the entire help file writing fraternity had gone bonkers or something else maybe wrong.
Clearing cache, using various mouse and keyboard combinations changed nothing. The fonts remained too small in the content area.
Forums, Microsoft and Yahoo Answers and other searches were not coming up with any results so I loaded Sysinternals Process Monitor, set some filters and nosed around the registry to find a bizarre call being made to some default entries buried deep under ‘International’ settings for Internet Explorer. It’s not surprising it has been difficult to fix, anyway, this is how you do it:-
How to change text size in chm help files
1. Download this .reg file unzip and double-click fix-font-in-chm.reg and follow instructions to change your registry.
Not so easy but less risk as you are in control of the changes
1. Open regedit
2. Navigate to HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\Scripts\3
3. Change IEFontSize to 03,00,00,00