This enhancement has been incorporated in Release 2009a (R2009a). For previous product releases, read below for any possible workarounds:
To increase the font size in the Help Window, please try the following:
1. In the MATLAB toolbar, navigate to File->Preferences
2. On the left hand bar of the Preferences Dialog Box, please expand the 'Fonts' heading and select 'Custom'
3. From the 'Desktop tools' menu, select 'HTML Proportional Text'
4. In the 'Font to use' section, increase the font size to a larger value.
5. Please close and re-open the Help Window in order to see the changes take effect.
Best Answer