Yahoo mail settings error accessed by Mint?
 

On a Mint 19 desktop my mother has Yahoo mail. Her friend borrowed use of her computer, now Yahoo mail doesn't work properly for her. Her email list is shortened to about ten new emails. Options she normally uses as faint and when clicked on, they don't respond. Is there a way to alter Yahoo setting back to normal?The settings button itself doesn't respond, but it seems mostly fine in Firefox. She usually uses Chromium.

Do I understand correctly that the problem is limited to Chromium and does not occur in Firefox?

If that is the case, you could try renaming the hidden Chromium dot-directory, then restart Chromium, which should create a new hidden dot-directory. If Yahoo mail then works properly, that would indicate that something went awry in one or more of the files therein. If there's no change, you can move the renamed directory back in place.