Highlight track one. Look for the music notes on left side of the tool options, just below the transitions icon. Take and lower the slider for track one volume for that clip down to 0. Now you will hear just track 2 audio.

Wnuk suggest using the Audio Mixing Room but the easiest way to mute an entire sound track is simply by unchecking the box to the left of the track. Video and audio can always be enabled (checked) or disabled (unchecked) separately...

An easy way to do well, click on the audio line in the position that you should switch to another track, (it appears a ball) and make a good ramp for smooth transition of audio, a better look at the attached image.
There's another divide and mutate to form the audio of one or another track.

If it is only for a specified duration that you want this switch, you can right-click on the opposing/offending clip (the one in track #1) and choose "Mute Clip".

Sorry, I kind of missed the word 'temporarily'. For that, I'd either go the way described by playsound or, if the transition should be immediate (as opposed to ramped), I'd split track 1 to make a clip aligned with the clip on track 2 and mute the former as mentioned by FredB...

the strange thing is that at various times during editing and previewing, I would and then would NOT hear the second audio track. I couldn't figure out what was different each time I tried to preview that clip/movie-mode, as I didn't seem to change anything.

I'm producing the final output now and hoping for the best!

Thanks for all the replies.
-AJ

I experienced audio dropouts while editing that I think were due to insufficient computing power. It was okay when I turned off the subtitle track (by unchecking its checkbox). The output produced should be fine although I didn't really try that as I only needed to export the subtitles into an srt file.