Hi
Make sure you retain the setup.exe file that you originally used to install your current version VP (6.20) ..put it somewhere safe just in case you need it. Ensure you have the registration code for that version.
Uninstall your current version of VP (6.20) including the data files using the PC control panel.
Go to... https://www.nchsoftware.com/videopad/index.html
and download the version there. This should be the .exe setup file for the earlier version of VP. (6.10) (You can check the version number in the download window) Double click the .exe file to install VP. Run the program and when prompted enter the registration code you obtained for VP 6.20
Nat