Add the image to the next highest video track.
Here you see the green audio linked to track one. Were it not needed it could be deleted.
If there are issues with a two-hour project, break it up into parts, export each and assemble them for the final export.
Of course, 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.