Hi @JackieZhang ,
Thank you for your post.
Yes - you can remote control from the latest version to older version.
Hope this information will help you.
Hi, I faced the same problem that connection failed when try to connect to an older version.
The remote TeamViewer is running an old version which is out of date, Therefore you cannot connect to this Version anymore. Your connection partner can update TeamViewer by clicking on "Help"-"Check for new version".
How to solve this without update the PC Team Viewer, because there is no one control that PC. It is quite far away from my current location.