Export thumbnail refresh fail

Overwriting a previously exported file fails to update the watermark if I have changed it for the new file. If I select a new watermark or watermark position when re-exporting a file, the watermark/watermark position does not change on the resulting file as viewed in LR. However the file is updated in Finder and when viewed in PShop. I am working in LR Classic 10.1.1 on a Mac.