Upon exit VP should be prompting to SAVE. Clicking the saved VPJ file will restore the project just as it was. Nothing should be displaced.
Open Videopad and prior to loading the project click OPTIONS | DISK tab and Clear Unused Cache Files, just in case the cache is corrupt.
It's a good idea to manually Save Project File AS regularly, giving it a unique # or name so as to not overwrite prior saves. Using Save Project Files (no AS) will overwrite. Then the appropriate VPJ file can be double-clicked, to load the program as it was when the file was written.
It's wise to edit and export with the same, or a close, version. But you can test the latest version. For licensed users upgrades are free for up to six months from purchase date. After that, VP will continue to fully function but a fee will be required in order to register the newest. Retain your old install file and registration info.