Sounds like a misunderstanding.
The media bin (top-left) contains files that have been imported - not completed projects.
Completed projects should be exported to the PC as video files. 
Play them from the PC directly.
When you play a clip in the media bin, only that clip is previewed. If you instead play the sequence, the currently loaded entire project will be seen.
When you SAVE a project, the VPJ control file is being updated. This is not an export. Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. From the HOME tab, the AS choice is available by clicking the caret to the right of the Save Project button on the toolbar. That way you're protected, and shouldn't lose anything.
Thus, you might have saved an 'unedited' version initially. After editing, use Save AS with a unique # or name. Double-click on a VPJ file and the project will load - just as it was when the file was saved. None of the project saves will be in the bin. Find them on the PC via a search or, in Videopad, click the three-lined Menu (top-left), click File, click Open Project and locate the desired project. Chances are that it will be in your Downloads folder..