When you say "recording a new video" - is this video a file that contains video and audio? What format? Share the file here...
Someone will check it out. Upload the file/s to a free server, such as Google Drive or MS OneDrive, get a shared (public) link, copy the link and paste it here or to me in a Private Message via the mail envelope in the top-right corner of this forum. When using Google Drive, if necessary change "restricted" to "anyone with link can view."
Install the current release and see if it does the same. For licensed users upgrades are free for up to six months from purchase date. After that, VP will continue to fully function but a fee will be required in order to register the newest. Retain your old install file and registration info.
Be sure that the balance slider at the left of the audio track is centered. 
If it's still an issue, open the file in WavePad. Ignore the option to open in Videopad.
Click the STEREO button, 
Click the caret and from the drop-down menu choose MONO. Click CONVERT and save the file. Back in Videopad, unlink the audio by right-clicking on the clip and making that choice. Then substitute the MONO file for the original.