Changing Automatic Filenames Text Size with Text Overlay version 10.25

[Russ Croucher]

I am creating many video files of slides that generate automatic filenames scrolling along the bottom but I cannot seem to change the filename text size.  It seemed to be stuck at 14.  I can go into each slide and edit the text box and change it to 8 which is my preferred but this is very time-consuming since I have 9000 slides convert.  Is there any way to have a default number different than 14?

The scroll left to right up and down all that is preserved but not the text size.

I've tried several different methods like outputting 3840x2160 and then downsizing it to 1920x1080 which will reduce the actual character size but that scroll speed is too fast.

I need some suggestions.  Is it possible?