How to increase the font size

There is no option to change the difficulty later in the game but you can use mods for that like: http://witcher.wikia.com/wiki/Difficulty_settings_mod

If you're on windows 7 (I think Vista as well?), try the following:

1. While Skyrim is running, alt-tab back to your desktop.
2. Click the volume icon in the system tray, then click "mixer".
3. In there, there are separate settings for each application currently running.
4. Move Skyrim's slider higher, and it should raise the volume relative to your other applications