Hmm, usually the view you see on Yahoo's website in Firefox is the same view you see in other email clients. However, I am not a big Yahoo user, so there may be some settings I don't know about that could hide folders.

What if you compare how Yahoo looks in another browser such as Microsoft Edge?

Looks the same in Microsoft edge as it does in Firefox

I wonder whether your Android mail program has a different view of the folders than what Yahoo shows in a browser. Can you do a mailbox search for something you see on your phone that's missing in Firefox/Edge and see whether you can track down where it is?

WHen I try to open one of the folders in Phone/ Android that is missing in PC/ Firefox, it just spins. Gone from there also, but the folder titles were retained. I guess they are all gone. THanks for helping.