I recommend you start reading the Wiki documentation on the GitHub website as it explains exactly how to work with the software and how to fix various issues. However, there is nothing about qTox and echo. I believe this is a setting that needs to be configured within the settings of the application.
Use the following link to reach the Wiki: https://github.com/qTox/qTox/wiki
Note: If you have an account GitHub, open a post and report this issue, as it always might be a bug in the application's code.