I can't seem to find a way to increase the frequencies shown on my spectral view. It appears to cut off around 15k, and I want to go up to 24ish. How can I do this?
What sample rate are you using? You will only be able to see frequencies up to the Nyquist limit for any given sample rate, so the highest frequency you will be able to record (and see) is 22.05kHz for a 44.1k sample rate, and 24kHz for a 48k rate.
The spectral view does in fact show all the frequencies present - you can't have it any other way, although the scaling when it's zoomed right out is a bit misleading. If you mouse over the scale, you can zoom in, and then drag the scale downwards to give you better resolution of higher frequencies (assuming that there's anything there to see, of course...)
My sound clip has sample rate of 48 kHz, but audition still shows up to 16 kHz in the spectrogram panel. How can I change the frequency range of spectrogram display?
If you are talking about the spectrum display below the waveform, then right-click on the scale of the spectrogram and select 'Full Linear'. That will display everything it's capable of. You can also zoom the scale from there using the mouse wheel.
You should bear in mind though that you'll only see frequencies that were recorded in the first place, and it would be very rare even to see meaningful content up to 20k under normal circumstances - ie, you aren't trying to record bats...