Lightroom 6.14 Export Date Format

My raw files are stored in folders by date taken: eg. 2025_7_24.  After processing in Lightroom I've exported them back to the same directory with a slight name change.  Lightroom still has instructions to 'export into same folder as original photo.  Recently Lightroom has started exporting to a new folder: eg 2025-7-24....using hyphens instead of underscores.  I'm at a loss how to g