Right-click the Windows speaker icon (in the tray at the bottom-right of the screen). Open the Volume Mixer and confirm that the Videopad slider is at 100%.
If necessary, increasing the gain in VP should not degrade the file as long as it's not overdriven.
Share the Audacity file and we'll analyze it...
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."