During uninstallation, the Clients and Servers folders (depending on the package that's being uninstalled) under the common application data (C:\ProgramData\QPR Software\QPR 2017\2017.1) is copied to Clients_old / Servers_old (or old1...oldN in the case more backup folders exist), and you're asked whether you want to remove the folder. In the case you have any customizations or you have used the example LocalDB database, it is safer to answer No and delete the old settings only after you've checked that you have all the material you want to keep with you.

 

Please note that the LocalDB engine is not uninstalled when the QPR Servers package is removed. If you need to remove it, please uninstall LocalDB from the Windows Control Panel.