Once you've updated screens and you're ready to replace old versions, you'll need to make sure they have the same file name, otherwise they'll upload as entirely new screens and won't be a part of your screen history.
Here’s how to replace your screens:
Go to the screen you want to replace.
Drag and drop the updated image into the browser. The screen will be replaced. If you want to replace multiple screens, try doing so from the prototype home page. Click the upload screens and drag and drop all of the images to replace them.
Once replaced all hotspots, templates and comments will remain in place.
To replace screens uploaded as PDFs, you'll need to upload via source files. This will initially sync all screens of the PDF and afterward will sync only the pages in the PDF that have been updated. Comments and hotspots will all remain in place.