I copied ny first Cassette to ipod format and have the following waveform (see first screen shot)
then I changed some setting so that the same waveform is much smaller in height - (see 2nd screen shot) - what setting do i change to get to where I can see the 1st waveform and its height
Neither waveform is optimal - the top one is too hot and is clipping (see the red lines) - the bottom one is too low.
Ideally you should try to aim for a waveform that maxes out at about 0.5 in the default linear display - this corresponds to about -6dB on the recording meters.
You can tweak the signal amplitude with the input slider on the mixer toolbar - see this page in the manual http://manual.audacityteam.org/o/man/mixer_toolbar.html
If you are using a USB device you may need to make the gain control on that hardware (assuming it has a gain control)