How does playback rate of an arbitrary waveform generator determine frequency content of that signal?
Capturing digital samples is a form of recording. Playing them back at a rate faster than the recording rate has the effect of frequency shifting the entire spectrum toward higher frequencies.

If you record a 100 Hz audio tone and play it back at 2x the original sample rate, it will become a 200 Hz audio tone. Etc. Hopefully this is enough information for you to understand the concept.

There are techniques which would allow you to playback audio faster, but with the same perceived pitch.

And it is also possible to "re-sample" a data series at a higher frequency, so that it can be played back at a different sample rate, and sound basically identical. But the re-sampling process cannot add new information. It is just a form of interpolation.