I don't believe there is a way to increase size of chm file text other than by the creator.

For my eyes the size of text in the contents panel is fine.

I purchased license yesterday and look forward to using this promising product.

Alex

I think part of that depends upon the verion of IE you are using (since CHM files are hosted within IE).  I know that on my development machine, the Ctrl+mouse wheel does not work within a CHM file, but it does work within IE by itself.  It's good to know that it works on your machine, Charles; it's certainly worth it for everyone to give it a try before attempting the other methods mentioned in this thread.