What do you mean?
To update the sofware to the latest version you need to first uninstall your old version and then install the new.
As regards your applications, I would take a copy or create a backup before opening the project in the new version so that you have a fall back position. Test your project in the new version to make sure everything still works as expected.
Usually you will need to make some changes, depending on how old your current version is
Hope this helps