For both UV/Vis and Vibration spectra, the spectral intensities are accompanied a plot of Lorentzian curves that approximate the appearance an actual spectra.  The width of the peaks in these spectra can be adjusted to be wider or narrower to make the plot appear more realistic.  For a set of spectra, each spectrum can be adjusted independently.  To adjust this width:

• On the spectrum of interest, click the right mouse button to bring up its context menu
   
• From the context menu, select Properties... at the bottom to bring up the Plot Properties Dialog
   
• In the field next to IR Peak Width (Vibration Spectra) or UV-Vis Peak Width (UV/Vis Spectra), type in the desired value and hit enter
   
• To accept the change and exit the Plot Properties Dialog, click the left mouse button on the okay button