The text under the toolbar buttons can be hidden by unchecking Show Toolbar Text Labels. The text under the graph buttons can be hidden by unchecking Show Graph Button Text Labels. The grid on the measurement thumbnails can be turned off by unchecking Show Grid on Thumbnails. Animate Task Panes controls whether the task panes (Target Settings etc) slide open and closed. General Font Size is the base font size (in points) for REW. Graph Font Size is the font size used for the graph axes. Font size changes do not take effect until REW is next started.
Suppress Soundcard Errors stops REW showing an error meassge if it cannot access a soundcard on startup, this may be used if REW is being used to analyse measurements on a computer without the audio niterfaces needed for making measurements.
If Confirm Unsave dMeasurement Removal is checked REW will ask for confirmation if you try to remove a measurement that has not been saved since it was last modified. This setting can also be changed from the removal confirmation dialog.
Under OS X Use OS X-style File Dialogs changes the file selection dialog to a format more like the native OS X file chooser, but note that the OS X-style chooser does not have the preview panel which REW uses to show the contents of mdat, req, calibration data and image files.