(To reproduce the symptom)
1. Click the "Start" button and then click "WordPad" from "Programs"-"Accessories".
2. Set the font to what you like and make a text with 12pt.
3. Click the "File" menu and then click "Save as".
4. When the "Save as" dialog box appears, type the location
and the file name you like and click the "Save" button to save the file.
5. Finish WordPad and open the file you have saved.
6. The font size of the text changes from 12pt to 10pt.
*This symptom occurs when a new file is created and saved for the first time. When some sentences are added to the filed once saved,
this symptom is unlikely to happen to the font of the added sentences.
When you save the text, save it in Rich Text Format instead of Word for Windows 6.0 Format.
It seems that you can avoid the symptom by making and saving the text with a font other than 12pt.