font size on mac g3

Your monitor rez is irrelevant as far as your font size. Setting the appearance control panel to display a larger font is the usual method to follow. If thats not working youre probably have either a missing font or a corrupt font. Replace that font from your system CD. While youre at it replace your whole fonts folder.

The problem is not the font size on the desktop screen.  It is the font displayed in ALL APPLICATION PROGRAMS, e.g. QuickBooks, Word, etc.  ALL FONTS and all pitches display on the screen as half size.  For example, Quick Books displays normally at 10 or 11 pitch and there is no way to control this.  On my screen the font displayed is about 5.5.  I don't think that the appearance control panel controls appearance within application programs, does it?

The appearance control panel will controll those fonts if the programs were written to take advantage of the systemwide appearance settings. In any case it sounds like you have missing or corrupt fonts that need to be replaced.

What fonts do you have available in your system folder? I ask this because the system appearance does use one of the system fonts such as Chicago or Charcoal -- make sure these are working okay and in your system fonts folder. Also make sure you have only one of these two fonts selected in the appearance control panel.

Does the problem occur when you boot the machine with extensions off )hold down the shift key during the boot cycle)?

Everthing is small, fonts, displays, everything.  If an application does not have a method of increasing diplay size, the windows are to small to see.  Everything in the window is too small.