Audacity should produce a mono WAV export if all the work on your timelines is mono and you have all your track pan controls centered. Are they and do you?
You can change the character of single blue-wave tracks with the drop-down menu from the little black arrow to the left of the track. Mono is one of the options.
If you have a stereo show in the production, you can convert it to mono by selecting it (click just above MUTE) and Tracks > Stereo Track to Mono.