borate Your intent is unclear. Open a text editor by clicking ADD TEXT on the toolbar. The resulting clip will appear in the bin (top-left) and on the next higher timeline track. To superimpose the text drag it to just above the mp4. Drag the text clip's borders to shorten or lengthen it.
DavidLE Yes, but I have a project that I've saved and when I reopen it, I can't access the editor to change the text.
borate Double-click the text clip on the track. Or double-click the text clip in the bin (top-left), then click on the small text box under the preview window. That will open the text editor.