Today I upgraded from Camtasia 8.3 to Camtasia 8.5 and ran into an issue with my audio settings only recording to the left speaker. I know that my microphone only records in mono so this was not surprising.
What was surprising is that the audio settings for the Camtasia Recorder were greyed out when using the TREC format.
In Camtasia 8.3 I could tell the Camtasia Recorder to record in mono so that it would be in both left and right speakers.
After a little bit of searching I came across this forum post that had the answer at the bottom.
When you are in Camtasia Studio, click on your clip, select audio options and check the mix to mono option.
Note: You may have to separate the audio from the video by right clicking on the clip and selecting the separate video and audio. Then click on the audio track and follow the steps above.
Problem solved and I can go back to finishing my video.