A couple of days ago I had to change my default browser from Firefox to Chrome to fix a problem on a particular company's web site. After I made Firefox the default browser again I found that every hyperlink in an email or a document that I clicked on opened Firefox at the same web page: "https://read.amazon.com/landing". I have no idea what I might have done to create this situation, let alone how to undo it. I am using Linux Mint with Firefox, Thunderbird and Libre Office. Peter