Blackman-Harris Spectral display

Your question is a little ambiguous. The Blackman-Harris display in Frequency Analysis follows the inventors' window function as designed, which you will find here.  If you want to know about the spectral display settings in Preferences, then the default resolution is 128, the dB range is 132, the grid line opacity is 15. Everything else you can alter you find by right-clicking on the frequency scale and there are effectively no defaults for these settings - you adjust them to suit what you are doing at the time.