Can't change erroneous protocol for HTML links in emails (Thunderbird)

When clicking on any web links embedded in emails in my server, Thunderbird, Wordpad opens. In Control Panel/Default Programs/Set Associations I have already set all possible htm-type links in the extensions section to my chosen browser, Opera. But in the protocols section, the protocols for FTP, HTTP and HTTPS are by default set to Wordpad. I have no idea why since Wordpad can't open HTML files. When I highlight these three protocols and click Change Program (protocol), I can't! There are no other choices given in the Change box...only Wordpad! This MUST be why T'bird defaults to Wordpad when I click on hyperlinks in my emails.

I am at a dead end. Please don't suggest to change file associations. As you can read, I've been there, done that! Is there any way to add Opera to the options so I can select it and remove Wordpad as the only choice?

Finally, if there is a work-around, what is the recommended protocol for FTP? Is it my FTP utility, WSFTP 95 or Windows Explorer?

Problem just solved! After installing a recent update to T'bird, I began having problems with FF refusing to open Yahoo and some other web portals. I removed Firefox and suddenly my system defaulted to WordPad(!) for opening htmls from emails. Definitely an impossibility!

So I installed Opera and found it opened the glitchy Yahoo sites easily. But merely installing it did not make it the default browser (maybe I missed that checkbox on installation?). Still T'bird insisted on handing that task to WordPad.

I discovered Thunderbird is passive and can only open HTML links in whichever browser you have selected as default. What's more, HTTP Protocol for programs like your email client can't be changed in Start/Default Program/Associate a File Type or Protocol...It must be changed from within your preferred browser.

So, under the dropdown menu accessed from the "Opera" icon on the upper left corner of the browser window, I went to Settings/Default Browser and selected Opera as my default browser.

Next time I clicked on and html links embedded in an email, it opened perfectly in Opera!