I installed Thunderbird 55.0a1 on top of an old Thunderbird email program and it started not responding and now I cannot view attachments So I thought I would do a clean install of Thunderbird but first needed to save files and folders. So,I downloaded the import/export add on for Thunderbird. When I went to download it, it asked what app would I like to use with it so I picked Adobe Acrobat Reader because I have loaded on the PC. Well it was an .xpi file which Adobe converted to a .pdf file and Adobe cannot open xpi files. I downloaded the add on again and it was downloaded as a .pdf file.
1) How do I convert it back to an .xpi file?
2) How can I prevent future downloads being downloaded as .pdf files?
3) How can I view email attachments, i.e. mp4's, jpg's mov. et?