Hi, never seen Gif on there or jiff before : https://support.mozilla.org/en-US/kb/applications-panel-set-how-firefox-handles-files

One way to get jpeg into the list if it is not there is to install something like this very good free program https://www.getpaint.net/ and let it add to the context menu and/or let it become the default opener for all supported file types as can always change that back.

One possible explanation is that a Firefox settings file has become corrupted. Another possible explanation is that some program has mucked up the Windows settings. I can suggest something to try for the first issue.

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" Help > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > Exit
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then rename handlers.json to something like handlersOLD.json. If you see a file named mimeTypes.rdf, rename that one to mimeTypesOLD.rdf.

Start Firefox back up again. Any improvement?

Also, to gain maximum control over files names as you save them:

(1) Set Firefox to ask you where you want to save downloads. This also allows you to edit the file name. You can set that here:

• Windows: "3-bar" menu button (or Tools menu) > Options
• Mac: "3-bar" menu button (or Firefox menu) > Preferences
• Linux: "3-bar" menu button (or Edit menu) > Preferences
• Any system: type or paste about:preferences into the address bar and press Enter/Return to load it

Scroll down to the Download section and click "Always ask you where to save files" (screenshot attached for reference).

(2) Set Windows to show all file extensions. See: https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/

Unfortunately that didn't work