The font size in the data sheet can be changed using the Window -> Text Size -> list menu. It would be nice if the current font size of the data sheet had a check mark in front of the pt size in the list. Then you would not have to guess what the current font size is.
If a change in the font size is the last action before closing the database then the font size is not automatically saved. In other words, if a change in the data sheet font size is the only change to a database, a manual save is required to keep the change.
Also, a change in the font size does not appear to be undoable since the Undo and Redo under the Edit menu are dimmed out.